Multi-layer microcapsule structure epsilon-CL-20 explosive crystal capable of resisting dissolution and inhibiting crystal change and preparation method of multi-layer microcapsule structure epsilon-CL-20 explosive crystal

Abstract

The invention relates to a multilayer microcapsule structure epsilon-CL-20 explosive crystal capable of resisting dissolution and inhibiting crystal change and a preparation method of the multilayer microcapsule structure epsilon-CL-20 explosive crystal, and belongs to the technical field of energetic materials. The core is composed of epsilon-CL-20 explosive crystals, the coating inner layer is formed by polydopamine, and the coating outer layer is composed of a fluorine-containing polymer with low surface tension and indissolvable characteristics and a functional additive. The functional auxiliary agent is a substance which has a surface activity effect on the fluorine-containing polymer. The structure endows the epsilon-CL-20 with hydrophobicity and a function of isolating liquid energetic components, the solubility of the epsilon-CL-20 is effectively reduced, meanwhile, the surface action between the epsilon-CL-20 and other components in a composite energetic material system is small due to low surface tension, the viscosity of the composite energetic material system is reduced, and the manufacturability is improved.

Description

Technical Field

[0001] The invention relates to a multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and crystal transformation inhibition and a preparation method thereof, belonging to the technical field of energetic materials. Background Art

[0002] Hexanitrohexaazaisowurtzitane (CL-20) is a nitramine compound with a cage-like molecular structure and a high energy density. Its density is 2.04 g / cm 3 , the theoretical detonation velocity reaches 9660m / s, and the detonation heat reaches 6.23MJ / kg. It is the third generation of energetic materials after RDX and HMX. However, CL-20 has multiple crystal forms, and four types have been separated and identified at room temperature and pressure, namely α, β, γ and ε. Among them, the density, energy and sensitivity of ε-CL-20 are relatively ideal. Studies have shown that ε-CL-20 will transform into β, γ or α crystal forms with lower density under certain conditions. This process is called the crystal transformation of ε-CL-20. After the crystal transformation of ε-CL-20, the crystal volume will expand and cracks will occur, which seriously affects its safety; in addition, the transformation of ε-CL-20 into other crystal forms will also lead to a decrease in the detonation, combustion performance and mechanical properties of the composite energetic material system.

[0003] Although a lot of research has been conducted on the crystallization, crystal form and crystal transformation of ε-CL-20 at home and abroad, most of them focus on the recrystallization in the preparation and production process of ε-CL-20, the self-crystallization process and kinetics of ε-CL-20 under thermal stimulation, etc. The bottleneck and scientific problem of ε-CL-20 in the field of composite energetic materials such as solid propellants, melt-cast explosives, and cast explosives is that the dissolution of ε-CL-20 under mechanical and thermal stimulation will induce crystal transformation, that is, ε-CL-20 is more likely to undergo crystal transformation under the action of dissolution. Therefore, to prevent the crystal transformation of ε-CL-20, it is necessary to first control the dissolution of ε-CL-20 in the composite energetic material system. Relevant studies at home and abroad have found that the starting temperature of the transformation of ε-CL-20 from the ε crystal form to the γ crystal form is about 135°C. In terms of inhibiting the crystal transformation of ε-CL-20, coating is often used at home and abroad to inhibit the crystal transformation of ε-CL-20. Coating ε-CL-20 with adhesives such as natural rubber, butadiene rubber, and terminal hydroxyl polybutadiene (HTPB) can inhibit the crystal transformation of ε-CL-20 to a certain extent and increase the crystal transformation temperature by 15~20°C, but this method is complicated and the degree of inhibition is limited; in terms of improving the solubility resistance of ε-CL-20, conventional coating methods are also commonly used at home and abroad to reduce the solubility of ε-CL-20 in the melt-casting carrier. For example, 2% perfluorooctanoic acid is used to coat ε-CL-20, which reduces the solubility of ε-CL-20 in ethyl acetate and 3,4-dinitropyrazole (DNP), but the disadvantage is that the mechanical properties of the particles are poor.

[0004] Coating is an important means to increase the crystal transformation temperature of ε-CL-20 and thus inhibit crystal transformation. Generally speaking, within a certain range, the thicker the coating thickness, the more the starting temperature of crystal transformation increases. However, the energy loss of ε-CL-20 explosive must also be considered. Combining these two aspects, the coating ratio cannot be too high. Therefore, it is necessary to control the coating thickness through appropriate methods and make the coating thickness more uniform. Only in this way can the solubility resistance of ε-CL-20 in organic solvents and melt-casting carriers be improved, and higher application value can be achieved.

[0005] In recent years, polydopamine has been widely used in the field of surface functionalization of energetic materials. Among them, the in-situ polymerization reaction of dopamine was used to coat the insensitive explosive triaminotrinitrobenzene (TATB) and HMX crystals to form a strong and dense core-shell structure. The use of dopamine to coat ε-CL-20 increased the self-crystallization temperature of ε-CL-20 under non-isothermal heating conditions by more than 30°C. In addition to enhancing the crystal stability and mechanical properties of energetic materials, the bonding effect of polydopamine between interfaces has also received great attention. In order to improve the adhesion between TATB and the adhesive, three substances, polyazide glycidyl ether, polyethylene glycol and polytetramethylene ether glycol, were bound to TATB particles through polydopamine. Although coating ε-CL-20 with polydopamine can increase the crystal transformation temperature of ε-CL-20 to a certain extent, the anti-dissolution performance of ε-CL-20 in the composite energetic material system still needs to be further improved. The existing method of combining the adhesive with the explosive crystal through polydopamine cannot improve the anti-dissolution and crystal transformation inhibition performance of ε-CL-20. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and anti-crystallization and a preparation method. The multi-layer microcapsule structure is used to modify the surface of the ε-CL-20 explosive crystal, so as to resist the dissolution of ε-CL-20 in the composite energetic material system and inhibit the crystallization of ε-CL-20. The multi-layer microcapsule structure is mainly composed of an inner layer formed by polydopamine and an outer layer composed of a fluorine-containing polymer as the main component with low surface tension and insoluble characteristics. The ε-CL-20 explosive crystal with a multi-layer microcapsule structure can effectively reduce the solubility of ε-CL-20 in a composite energetic material system containing a liquid component and having a dissolving effect on ε-CL-20, effectively inhibit the crystallization of ε-CL-20 caused by dissolution, and increase the self-crystallization temperature of ε-CL-20, improve the crystal stability of ε-CL-20, thereby improving the safety, processability and mechanical properties of ε-CL-20-based composite energetic materials.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows.

[0008] A multi-layer microcapsule structured ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation comprises a core composed of ε-CL-20 explosive crystals, an inner coating layer formed of polydopamine, and an outer coating layer composed of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive; the functional additive is a substance that has a surface active effect on the fluorine-containing polymer.

[0009] Preferably, taking the total mass of the ε-CL-20 explosive crystals with the multi-layer microcapsule structure having anti-dissolution and inhibited crystal transformation as 100%, the mass fractions of the components are as follows: ε-CL-20 explosive crystals 92~97.5%, the coating inner layer 0.5~4%, and the coating outer layer 2~4%.

[0010] Preferably, based on the total mass of the coated outer layer as 100%, the mass fraction of the fluorine-containing polymer is 85% to 90%, and the mass fraction of the functional additive is 10 to 15%.

[0011] A method for preparing a multi-layer microcapsule structured ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation comprises the following steps: (1) mixing ε-CL-20 explosive crystals, dopamine monomers and weakly alkaline buffer solution I, allowing the dopamine monomers to self-polymerize under mechanical stirring to form a polydopamine coating inner layer on the surface of the ε-CL-20 explosive crystals, and performing solid-liquid separation and washing to obtain ε-CL-20 having a single-layer microcapsule structure; Dissolving the fluorine-containing polymer and the functional additive in an organic solvent to form a homogeneous polymer solution; the functional additive is a substance that has a surface active effect on the fluorine-containing polymer; the organic solvent is a solvent that dissolves the fluorine-containing polymer but has no obvious dissolving effect on ε-CL-20; (2) mixing the ε-CL-20 having a single-layer microcapsule structure with a weakly alkaline buffer solution II, and heating the mixture to a target temperature to obtain a mixture; the target temperature is 10±5° C. below the boiling point of the organic solvent in step (1) and does not exceed 100° C.; (3) adding the homogeneous polymer solution dropwise to the mixture by a water suspension method, mechanically stirring until the organic solvent is completely volatilized, separating the solid and liquid, washing, and drying to obtain a multi-layer microcapsule structure ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation; Wherein, the weak alkaline buffer solution I and the weak alkaline buffer solution II are buffer solutions with a pH value of 8 to 8.5.

[0012] Preferably, in step (1), the weakly alkaline buffer solution I is a tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and the concentration is preferably 5-10 mmol / L.

[0013] Preferably, in step (1), the mass ratio of the ε-CL-20 explosive crystals to the weakly alkaline buffer solution I is 1:5 to 1:10.

[0014] Preferably, in step (1) and step (3), the mechanical stirring is ultrasonic vibration, magnetic stirring, oscillation or paddle stirring, more preferably paddle stirring.

[0015] Preferably, in step (1), the dopamine monomer is dopamine, levodopa, 1-(3,4-dihydroxyphenyl)-2-aminoethanol or 6-hydroxydopamine.

[0016] Preferably, in step (1), the fluorine-containing polymer is one or more of polyvinylidene fluoride, ethylene-polytetrafluoroethylene copolymer and polychlorotrifluoroethylene.

[0017] Preferably, in step (1), the functional auxiliary agent is polyvinyl pyrrolidone, polyethanol, perfluoroalkanoic acid or perfluoroalkanoic acid salt, more preferably polyvinyl pyrrolidone or perfluorooctanoic acid.

[0018] Preferably, in step (1), the organic solvent is tetrahydrofuran or a tetrahydrofuran / N-methylpyrrolidone mixture, more preferably tetrahydrofuran.

[0019] Preferably, in step (2), the weakly alkaline buffer II is a buffer having a pH value of 8 to 8.5, preferably a tris(hydroxymethyl)aminomethane hydrochloride buffer, and the concentration is preferably 5 to 10 mmol / L.

[0020] Preferably, in step (2), the mass ratio of the ε-CL-20 having a single-layer microcapsule structure to the weakly alkaline buffer solution II is 1:5 to 1:10.

[0021] Preferably, in step (2), the target temperature is 60±5°C.

[0022] Preferably, in step (3), the solid-liquid separation is suction filtration.

[0023] Preferably, in step (3), the washing is performed by successively rinsing with anhydrous ethanol and distilled water.

[0024] Preferably, in step (3), the drying is carried out in an oven at a drying temperature of 55° C. to 65° C. and a drying time of 4 h to 6 h.

[0025] Beneficial Effects The ε-CL-20 explosive crystal with a multi-layer microcapsule structure adopts an outer layer with a fluorine-containing polymer as the main component with low surface tension and insoluble characteristics. This structure gives ε-CL-20 hydrophobicity and the function of isolating liquid energetic components, effectively reducing the solubility of ε-CL-20. At the same time, the low surface tension also reduces the surface interaction between ε-CL-20 and other components in the composite energetic material system, reduces the viscosity of the composite energetic material system, and is conducive to improving the processability.

[0026] The ε-CL-20 explosive crystal with a multi-layer microcapsule structure uses an inner layer formed by polydopamine. This structure gives ε-CL-20 a higher autocrystal transformation temperature and improves the crystal stability of ε-CL-20. At the same time, the viscosity of dopamine enables the outer layer to be stably attached to the surface of ε-CL-20.

[0027] The method of surface modification of ε-CL-20 explosive crystals using a multi-layer microcapsule structure only requires that ε-CL-20 and dopamine monomers be placed in a buffer solution and stirred at room temperature and pressure, which is simple to operate and has a safe process. The improved water suspension method has a mature and safe process. The innovation lies in replacing the water in the original method, using a buffer solution as a medium to increase the activity of the inner layer of dopamine, and utilizing the adhesion of the outer layer. The method of surface modification of ε-CL-20 explosive crystals using a multi-layer microcapsule structure of the present invention has the advantages of simple operation and safe process.

[0028] The ε-CL-20 explosive crystals with a multi-layer microcapsule structure of the present invention are capable of resisting the dissolution of liquid components in a composite energetic material system, such as trinitrotoluene (TNT), dinitroanisole (DNAN), nitroglycerin (NG), butanetriol trinitrate (BTTN), etc., thereby inhibiting the crystal transformation of ε-CL-20 in such composite energetic material systems. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with specific embodiments.

[0030] According to a first aspect of the present invention, the present invention provides a multi-layer microcapsule structure ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation, wherein the ε-CL-20 explosive crystal comprises a core composed of ε-CL-20 explosive, an inner layer formed of polydopamine, and a coating outer layer composed of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive; Based on the total weight of the ε-CL-20 explosive crystal, the content of the ε-CL-20 explosive is 92-97.5%, the content of the inner layer formed by the polydopamine is 0.5-4%, and the content of the outer layer composed of the fluorine-containing polymer with low surface tension and poor solubility and the functional additive is 2-4%. Furthermore, the functional additive accounts for 10-15% of the total weight of the outer layer.

[0031] According to the second aspect of the present invention, the present invention provides a method for preparing a multi-layer microcapsule structured ε-CL-20 explosive crystal that is resistant to dissolution and inhibits crystal transformation, the method comprising self-polymerizing dopamine monomers in the core of the ε-CL-20 explosive to obtain ε-CL-20 having a single-layer microcapsule structure, and obtaining ε-CL-20 explosive crystals having a multi-layer microcapsule structure using an improved water suspension method.

[0032] In the following examples and comparative examples: ε-CL-20 explosive: Liaoning Qingyang Special Chemical Co., Ltd.; Dopamine hydrochloride, levodopa, 1-(3,4-dihydroxyphenyl)-2-aminoethanol, and 6-hydroxydopamine were purchased from Sigma-Aldrich Reagent Co., Ltd. Polyvinylidene fluoride, ethylene-polytetrafluoroethylene copolymer, polychlorotrifluoroethylene: purchased from Daikin Industries, Ltd.; Polyvinyl pyrrolidone, polyethanol, perfluorooctanoic acid, ammonium perfluorooctanoate, tris(hydroxymethyl)aminomethane hydrochloride buffer, ethanol, distilled water, tetrahydrofuran, and N-methylpyrrolidone were purchased from MacLean Biochemical Technology Co., Ltd.

[0033] Example 1 A multi-layer microcapsule structured ε-CL-20 explosive crystal with anti-dissolution and anti-crystal transformation properties, comprising, by mass, 97.5% of ε-CL-20 explosive crystals, 0.5% of an inner layer formed of polydopamine, and 2% of an outer coating layer consisting of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive.

[0034] A method for preparing a multi-layer microcapsule structured ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation comprises the following steps: (1) 97.5% of ε-CL-20 explosive crystals, 0.5% of dopamine monomer L-DOPA and 5 times the mass of ε-CL-20 weak alkaline buffer (Tris(hydroxymethyl)aminomethane hydrochloride buffer with a pH value of 8.5 and a concentration of 10 mmol / L) were mixed. L-DOPA was self-polymerized for 6 hours under mechanical stirring (oscillation) to form an inner layer composed of polydopamine on the surface of the ε-CL-20 explosive crystals, thereby obtaining ε-CL-20 with a single-layer microcapsule structure.

[0035] (2) A mixture of weak alkaline buffer and ε-CL-20 having a single-layer microcapsule structure is filtered using a Buchner funnel, and washed in the funnel first with anhydrous ethanol and then with distilled water until the unattached polydopamine is washed away.

[0036] (3) 1.8% polychlorotrifluoroethylene copolymer and 0.2% ammonium perfluorooctanoate were dissolved in a tetrahydrofuran / N-methylpyrrolidone mixed solvent (the mass ratio of tetrahydrofuran to N-methylpyrrolidone was 9:1) to form a homogeneous polymer solution.

[0037] (4) The washed ε-CL-20 having a single-layer microcapsule structure was mixed with a new weakly alkaline buffer solution (Tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH value of 8.5 and a concentration of 10 mmol / L) at a mass ratio of 1:10 and heated to 60°C.

[0038] (5) adding the homogeneous polymer solution obtained in step (3) dropwise to the mixture obtained in step (4) by a water suspension method, and mechanically stirring (vibrating) until all the organic solvent is evaporated.

[0039] (6) The mixture obtained in step (5) is subjected to solid-liquid separation, washing, and drying (drying in an oven at a drying temperature of 60° C. for a drying time of 4 h) to obtain the ε-CL-20 explosive crystals having a multilayer microcapsule structure.

[0040] Example 2 A multi-layer microcapsule structured ε-CL-20 explosive crystal with anti-dissolution and anti-crystal transformation properties, comprising, by mass, 92% of ε-CL-20 explosive crystals, 4% of an inner layer formed of polydopamine, and 4% of an outer coating layer consisting of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive.

[0041] A method for preparing a multi-layer microcapsule structured ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation comprises the following steps: (1) 92% of ε-CL-20 explosive crystals, 4% of dopamine monomer 6-hydroxydopamine and 10 times the mass of ε-CL-20 weak alkaline buffer (Tris(hydroxymethyl)aminomethane hydrochloride buffer with a pH value of 8.5 and a concentration of 10 mmol / L) were mixed. Under mechanical stirring (magnetic stirring), 6-hydroxydopamine was self-polymerized for 12 hours to form an inner layer composed of polydopamine on the surface of the ε-CL-20 explosive crystals, thereby obtaining ε-CL-20 with a single-layer microcapsule structure.

[0042] (2) A mixture of weak alkaline buffer and ε-CL-20 having a single-layer microcapsule structure is filtered using a Buchner funnel, and washed in the funnel first with anhydrous ethanol and then with distilled water until the unattached polydopamine is washed away.

[0043] (3) 3.5% ethylene-polytetrafluoroethylene copolymer and 0.5% perfluorooctanoic acid were dissolved in tetrahydrofuran to form a homogeneous polymer solution.

[0044] (4) The washed ε-CL-20 having a single-layer microcapsule structure was mixed with a new weakly alkaline buffer solution (Tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH value of 8.5 and a concentration of 10 mmol / L) at a mass ratio of 1:5 and heated to 55°C.

[0045] (5) The homogeneous polymer solution obtained in step (3) is added dropwise to the mixture obtained in step (4) by a water suspension method, and mechanically stirred (magnetically stirred) until all the organic solvent is evaporated.

[0046] (6) The mixture obtained in step (5) is subjected to solid-liquid separation, washing, and drying (drying in an oven at a drying temperature of 55° C. for a drying time of 6 h) to obtain the ε-CL-20 explosive crystals having a multi-layer microcapsule structure.

[0047] Example 3 A multi-layer microcapsule structured ε-CL-20 explosive crystal with anti-dissolution and anti-crystal transformation properties, comprising, by mass, 94% of ε-CL-20 explosive crystals, 2% of an inner layer formed of polydopamine, and 4% of an outer coating layer consisting of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive.

[0048] A method for preparing a multi-layer microcapsule structured ε-CL-20 explosive crystal that resists dissolution and inhibits crystal transformation comprises the following steps: (1) 94% of ε-CL-20 explosive crystals, 2% of dopamine monomer dopamine hydrochloride and 5 times the mass of ε-CL-20 weak alkaline buffer (Tris(hydroxymethyl)aminomethane hydrochloride) buffer with a pH value of 8.5 and a concentration of 10 mmol / L) were mixed. Dopamine hydrochloride was self-polymerized for 6 hours under mechanical stirring (paddle stirring) to form an inner layer composed of polydopamine on the surface of the ε-CL-20 explosive crystals, thereby obtaining ε-CL-20 with a single-layer microcapsule structure.

[0049] (2) A mixture of weak alkaline buffer and ε-CL-20 having a single-layer microcapsule structure is filtered using a Buchner funnel, and washed in the funnel first with anhydrous ethanol and then with distilled water until the unattached polydopamine is washed away.

[0050] (3) 3.5% polyvinylidene fluoride and 0.5% polyvinyl pyrrolidone are dissolved in a tetrahydrofuran / N-methylpyrrolidone mixed solvent to form a homogeneous polymer solution.

[0051] (4) The washed ε-CL-20 having a single-layer microcapsule structure was mixed with a new weakly alkaline buffer solution (Tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH value of 8.5 and a concentration of 10 mmol / L) at a mass ratio of 1:5 and heated to 60°C.

[0052] (5) The homogeneous polymer solution obtained in step (3) is added dropwise to the mixture obtained in step (4) by a water suspension method, and mechanically stirred (by blades) until all the organic solvent is evaporated.

[0053] (6) The mixture obtained in step (5) is subjected to solid-liquid separation, washing, and drying to obtain the ε-CL-20 explosive crystals having a multi-layer microcapsule structure.

[0054] In order to illustrate the effect of the present invention, this specification lists untreated ε-CL-20, the solubility of the liquid components of three embodiments of the present invention in different composite energetic systems, and the crystal transformation rate after the process.

[0055] The solubility of the above-mentioned ε-CL-20 in TNT, DNAN and BTTN at 100°C was measured by liquid chromatography. The results are shown in Table 1 below: Table 1 Compared with the untreated ε-CL-20, the solubility of the three examples in the three liquid components is significantly reduced, indicating that the ε-CL-20 explosive crystals with a multi-layer microcapsule structure play a key role in reducing the solubility of CL-20.

[0056] XRD was used to determine the crystal forms of untreated ε-CL-20 and CL-20 treated by corresponding processes in different liquid components according to the three embodiments of the present invention. The content of the crystal form is shown in Table 2 below: Table 2 The three examples are compared with the untreated ε-CL-20. The crystal purity after the liquid component treatment is significantly higher than that of the treated ε-CL-20, indicating that the ε-CL-20 explosive crystal with a multi-layer microcapsule structure plays a key role in improving the stability of the ε-CL-20 crystal. Since the crystal change of ε-CL-20 is mainly caused by dissolution, the lower the solubility, the higher the crystal purity.

[0057] In summary, the ε-CL-20 explosive crystal with a multi-layer microcapsule structure of the present invention has good resistance to dissolution and improves the stability of the ε-CL-20 crystal form.

[0058] In summary, the invention includes but is not limited to the above embodiments. Any equivalent substitution or partial improvement made under the spirit and principle of the invention shall be deemed to be within the protection scope of the invention.

Claims

1. A multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and anti-crystal transformation, characterized by: The core is composed of ε-CL-20 explosive crystals, the inner coating layer is formed of polydopamine, and the outer coating layer is composed of a fluorine-containing polymer with low surface tension and poor solubility and a functional additive; the functional additive is a substance that plays a surface active role on the fluorine-containing polymer.

2. The multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and anti-crystallization properties as claimed in claim 1, characterized in that: Taking the total mass of the multi-layer microcapsule structured ε-CL-20 explosive crystals with anti-dissolution and anti-crystal transformation as 100%, the mass fractions of the components are as follows: ε-CL-20 explosive crystals 92-97.5%, inner coating layer 0.5-4%, and outer coating layer 2-4%.

3. The multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and anti-crystallization properties as claimed in claim 2, characterized in that: Taking the total mass of the outer coating layer as 100%, the mass fraction of the fluorine-containing polymer is 85% to 90%, and the mass fraction of the functional additive is 10 to 15%.

4. A method for preparing the multi-layer microcapsule structure ε-CL-20 explosive crystal with anti-dissolution and anti-crystallization properties as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) mixing ε-CL-20 explosive crystals, dopamine monomers and weakly alkaline buffer solution I, allowing the dopamine monomers to self-polymerize under mechanical stirring to form a polydopamine coating inner layer on the surface of the ε-CL-20 explosive crystals, and performing solid-liquid separation and washing to obtain ε-CL-20 having a single-layer microcapsule structure; Dissolving the fluorine-containing polymer and the functional additive in an organic solvent to form a homogeneous polymer solution; the functional additive is a substance that has a surface active effect on the fluorine-containing polymer; the organic solvent is a solvent that dissolves the fluorine-containing polymer but has no obvious dissolving effect on ε-CL-20; (2) mixing the ε-CL-20 having a single-layer microcapsule structure with a weakly alkaline buffer solution II, and heating the mixture to a target temperature to obtain a mixture; the target temperature is 10±5° C. below the boiling point of the organic solvent in step (1) and does not exceed 100° C.; (3) adding the homogeneous polymer solution dropwise to the mixture by a water suspension method, mechanically stirring until the organic solvent is completely volatilized, separating the solid from the liquid, washing, and drying to obtain an ε-CL-20 explosive crystal with a multi-layer microcapsule structure that resists dissolution and inhibits crystal transformation; Wherein, the weak alkaline buffer solution I and the weak alkaline buffer solution II are buffer solutions with a pH value of 8 to 8.

5.

5. The method for preparing a dissolution-resistant and crystal-transformation-inhibiting multi-layer microcapsule structure ε-CL-20 explosive crystal according to claim 4, characterized in that: In step (1), the weak alkaline buffer I is a tris(hydroxymethyl)aminomethane hydrochloride buffer with a concentration of 5 to 10 mmol / L; in step (2), the weak alkaline buffer II is a tris(hydroxymethyl)aminomethane hydrochloride buffer with a concentration of preferably 5 to 10 mmol / L.

6. The method for preparing a dissolution-resistant and crystal-transformation-inhibiting multi-layer microcapsule structure ε-CL-20 explosive crystal according to claim 4, characterized in that: In step (1), the mass ratio of the ε-CL-20 explosive crystals to the weak alkaline buffer solution I is 1:5 to 1:10; in step (2), the mass ratio of the ε-CL-20 having a single-layer microcapsule structure to the weak alkaline buffer solution II is 1:5 to 1:

10.

7. The method for preparing a dissolution-resistant and crystal-transformation-inhibiting multi-layer microcapsule structured ε-CL-20 explosive crystal according to claim 4, characterized in that: In step (1), the dopamine monomer is dopamine, levodopa, 1-(3,4-dihydroxyphenyl)-2-aminoethanol or 6-hydroxydopamine; The fluorine-containing polymer is one or more of polyvinylidene fluoride, ethylene-polytetrafluoroethylene copolymer and polychlorotrifluoroethylene; The functional auxiliary agent is polyvinyl pyrrolidone, polyethanol, perfluoroalkanoic acid or perfluoroalkanoic acid salt; more preferably, polyvinyl pyrrolidone or perfluorooctanoic acid. The organic solvent is tetrahydrofuran or a mixture of tetrahydrofuran and N-methylpyrrolidone, more preferably tetrahydrofuran.

8. The method for preparing the multi-layer microcapsule structure ε-CL-20 explosive crystals with anti-dissolution and anti-crystallization properties as claimed in claim 4, characterized in that: In step (2), the target temperature is 60±5°C.

9. The method for preparing the multi-layer microcapsule structure ε-CL-20 explosive crystals with anti-dissolution and anti-crystallization properties as claimed in claim 4, characterized in that: In step (3), the solid-liquid separation is suction filtration; The washing is performed by washing with anhydrous ethanol and distilled water in sequence; The drying is carried out in an oven at a temperature of 55° C. to 65° C. for a drying time of 4 h to 6 h.

10. The method for preparing a dissolution-resistant and crystal-transformation-inhibiting multi-layer microcapsule structured ε-CL-20 explosive crystal according to any one of claims 4 to 9, characterized in that: In step (1) and step (3), the mechanical stirring is ultrasonic vibration, magnetic stirring, oscillation or paddle stirring; more preferably, it is paddle stirring.

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