Potassium nitrate material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of KNO3 materials, and particularly discloses a potassium nitrate material and a preparation method and application thereof.The preparation method comprises the steps that an inorganic separant is placed in a reaction container, a first solvent is added, ultrasonic dispersion is conducted, and isolation dispersion liquid is obtained; adding KNO3 and an anti-blocking agent into the isolated dispersion liquid, heating, stirring and adsorbing to obtain an isolated potassium nitrate suspension; dissolving an organic coating agent in a second solvent to obtain a coating solution, dropwise adding the coating solution into the isolated potassium nitrate turbid liquid under a stirring condition, raising the temperature of a reaction system while dropwise adding the coating solution, continuing stirring reaction after dropwise adding, and then filtering, cleaning and drying to obtain the inorganic-organic hybrid membrane coated potassium nitrate material. The potassium nitrate material coated with the inorganic-organic hybrid membrane has the advantages of being resistant to caking and good in isolation effect with components such as AP.

Description

Technical Field

[0001] The invention relates to the technical field of KNO3 materials, and in particular to a potassium nitrate material and a preparation method and application thereof. Background Art

[0002] The crystal density of potassium nitrate (KNO3) is 2.11 g / cm 3 , the decomposition temperature is 334 ° C, it does not absorb moisture when stored alone, and is a common inorganic compound. It is widely used in agriculture, food industry, explosives, medicine and other fields. Potassium nitrate is a strong oxidant. Potassium nitrate has the advantages of low cost, easy availability and high stability, and occupies an important position in the field of solid propellants.

[0003] However, KNO3 faces two major problems in its application: first, it is easy to agglomerate, which makes it difficult to transport and use; second, it is easy to absorb moisture when mixed with common components in propellants such as AP, which makes it difficult to adapt to high temperature and high humidity storage environments; these two problems seriously restrict the engineering application of KNO3. Therefore, solving the above two problems is a necessary condition for realizing the further application of KNO3 in solid propellants and other fields.

[0004] At present, most of the reports on KNO3 at home and abroad focus on the anti-caking technology of fertilizers. There are few reports on the strong moisture absorption phenomenon when KNO3 and AP are mixed in the propellant system. In the anti-caking technology of fertilizers, the method of adding anti-caking agents is mainly adopted. British researchers have characterized the caking tendency of NPK granular fertilizer (nitrogen, phosphorus and potassium compound fertilizer) through two accelerated caking tests, and the presence of free water in the fertilizer particles further accelerates its caking speed. Domestic researchers have shown through experiments that when the surface of urea particles has a large water content, the dispersed urea particles are easy to stick together under the evaporation of water caused by temperature changes and the extrusion between particles caused by pressure. The research results of domestic and foreign scholars show that controlling the free water on the surface of KNO3 particles and reducing the contact between particles are the main ways to overcome the agglomeration and moisture absorption of KNO3 particles. However, the single addition of anti-caking agents has failed to fundamentally solve the agglomeration and moisture absorption problems of potassium nitrate. Potassium nitrate still clumps severely after being stacked for a period of time. Summary of the invention

[0005] In view of the above problems, the first object of the present invention is to provide a method for preparing potassium nitrate material. The method starts from the nature of agglomeration and hygroscopicity of KNO3 material, and obtains inorganic-organic hybrid membrane-coated potassium nitrate material through the free adsorption of isolation agent by KNO3 material, and then supplemented by in-situ coating and fixation of coating agent and anti-caking agent; the preparation method is simple and easy to operate.

[0006] The second object of the present invention is to provide the above-mentioned inorganic-organic hybrid membrane-coated potassium nitrate material, which has the advantages of stability, low coating amount, anti-caking, and good isolation effect from components such as AP.

[0007] The third object of the present invention is to provide the use of the above-mentioned inorganic-organic hybrid membrane-coated potassium nitrate material in the preparation of propellants, explosives or other energetic materials.

[0008] The first technical solution adopted by the present invention is: a method for preparing potassium nitrate material, comprising the following steps:

[0009] S1: placing an inorganic isolating agent in a reaction container and adding a first solvent, and ultrasonically dispersing the inorganic isolating agent to obtain an isolating dispersion; the inorganic isolating agent is one or more of nano-hydrophobic SiO2, carbon nanotubes, fluorinated graphene and nano-silver particles;

[0010] S2: adding KNO3 and an anti-caking agent to the isolated dispersion, heating, stirring, and adsorbing to obtain an isolated potassium nitrate suspension;

[0011] S3: dissolving the organic coating agent in the second solvent to obtain a coating liquid, and dropping the coating liquid into the isolated potassium nitrate suspension under stirring conditions, while increasing the temperature of the reaction system while dropping the coating liquid, and continuing to stir the reaction after the dropping is completed, followed by filtering, washing, and drying to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0012] Preferably, the added amount of the inorganic isolation agent is 0.1wt% to 2wt% of the amount of KNO3.

[0013] Preferably, the anti-caking agent is one or more of calcium phosphate, calcium carbonate, calcium silicate, titanium dioxide and aluminum silicate; the added amount of the anti-caking agent is 0.2wt% to 2wt% of the amount of KNO3.

[0014] Preferably, the organic coating agent is one or more of polystyrene, polyethylene oxide, polyethylene terephthalate, polymethyl methacrylate, fluororubber and polytetrafluoroethylene; the added amount of the organic coating agent is 1wt% to 5wt% of the amount of KNO3.

[0015] Preferably, the first solvent is one or more of chloroform, cyclohexane, and n-hexane; the amount of the first solvent is 15 mL / gKNO3-30 mL / gKNO3;

[0016] The second solvent is one or more of toluene, xylene, ethanol, ethyl acetate, acetonitrile, and acetone; the amount of the second solvent used ranges from 5 mL to 20 mL.

[0017] Preferably, the step S1 comprises:

[0018] Under room temperature conditions, an inorganic isolating agent is placed in a reaction container and a first solvent is added, and the inorganic isolating agent is ultrasonically dispersed in the first solvent by an ultrasonic cell pulverizer to obtain an isolated dispersion liquid; the working mode of the ultrasonic cell pulverizer is an intermittent mode, the power is 1KW, and the ultrasonic time is 5-20min.

[0019] Preferably, step S2 comprises:

[0020] Add KNO3 and an anti-caking agent to the isolated dispersion, heat to 30°C to 55°C, and stir and adsorb at a stirring speed of 200rpm to 400rpm for 2 to 4 hours to obtain an isolated potassium nitrate suspension.

[0021] Preferably, step S3 comprises:

[0022] The organic coating agent is dissolved in the second solvent to obtain a coating liquid, and the coating liquid is added dropwise to the isolated potassium nitrate suspension at a rate of 0.2 mL / min to 5 mL / min under stirring. While adding the coating liquid II, the temperature of the reaction system is increased to 40°C to 65°C. After the addition is completed, the reaction is continued to be stirred at a stirring speed of 200 rpm to 400 rpm for 2 to 4 hours, followed by filtering, washing and drying to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0023] The second technical solution adopted by the present invention is: an inorganic-organic hybrid membrane-coated potassium nitrate material prepared by the preparation method described in the first technical solution.

[0024] The third technical solution adopted by the present invention is: use of an inorganic-organic hybrid membrane-coated potassium nitrate material in the preparation of propellants, explosives or other energetic materials.

[0025] Beneficial effects of the above technical solution:

[0026] (1) The preparation method of a potassium nitrate material provided by the present invention starts from the nature of agglomeration and moisture absorption of KNO3 material, and obtains an inorganic-organic hybrid membrane-coated potassium nitrate material through solid-phase nano-adsorption of KNO3 material on an isolation agent, and then supplemented with in-situ coating and fixation of a coating agent and an anti-caking agent. On the one hand, the addition of the isolation agent can effectively block the contact between the KNO3 material and the particles of components such as AP, thereby reducing the diffusion of salt ions in the liquid film layer on the surface of the KNO3 material at a microscopic level and reducing the moisture absorption rate of the material. On the other hand, the organic coating agent added later further blocks the diffusion of water molecules and can also fix the adsorbed isolation agent, so that the inorganic-organic hybrid membrane-coated potassium nitrate material has the advantages of stability, low coating amount, anti-caking, and good isolation effect with components such as AP.

[0027] (2) The present invention innovatively uses the "solid phase nano-adsorption method" to adsorb the nano-inorganic isolation agent on the surface of the KNO3 material, which has a simple reaction, good isolation effect and good reproducibility.

[0028] (3) Compared with the conventional method of directly adding an anti-caking agent, the present invention uses solid-phase nano-adsorption of the isolation agent by KNO3 material, and then uses the in-situ coating and fixation of the coating agent and the anti-caking agent to effectively solve the problem that potassium nitrate produced by the traditional method still has serious agglomeration after being stacked for a period of time. The preparation method is simple and easy to industrialize. The product is stable and has a low coating amount. It can effectively solve the strong moisture absorption phenomenon when KNO3 and ammonium perchlorate (AP) are mixed in the propellant system, and achieve excellent anti-hygroscopic effect. This method can be extended to solve the problem of deterioration of hygroscopicity of other mixed hygroscopic materials.

[0029] (4) The present invention has experimentally found that when KNO3 and AP are stored separately, the saturated moisture absorption rate is low (at 25°C and 75% RH, the saturated moisture absorption rates of KNO3 and AP are 0% and 0.5%, respectively), but the moisture absorption rate increases sharply after the two are mixed (at 25°C and 75% RH, the 168h moisture absorption rate of the mixed sample of KNO3 and AP is about 17%), which seriously affects its application in propellants. After adding a small amount of agglomerating agent, the moisture absorption rate is reduced to a certain extent (at 25°C and 75% RH, the 168h moisture absorption rate of the mixed sample of KNO3 and AP with 1wt% anti-caking agent is 10.2%), and the anti-moisture absorption effect is significantly weakened after being extruded and stirred in a mixer. This shows that the traditional method has a weak isolation effect on the two, and has a poor interaction with the KNO3 material, making it difficult to apply in practice. A large number of experiments have shown that the inorganic-organic hybrid membrane-coated potassium nitrate material prepared by the present invention is used for solid propellants, which can significantly reduce the moisture absorption rate of solid propellant blocks and has a good isolation effect from components such as AP. The composite material has good application prospects in the fields of solid propellants, explosives, pyrotechnics, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a SEM image of the KNO3 raw material in Example 1 of the present invention;

[0031] Figure 2 This is the EDS spectrum of the KNO3 raw material in Example 1 of the present invention;

[0032] Figure 3 This is a SEM image of the potassium nitrate material coated with the inorganic-organic hybrid membrane in Example 1 of the present invention;

[0033] Figure 4 This is the EDS spectrum of the potassium nitrate material coated with the inorganic-organic hybrid membrane in Example 1 of the present invention;

[0034] Figure 5 The moisture absorption rate-time curve of the KNO3 raw material, the potassium nitrate material coated with an inorganic-organic hybrid membrane, the AP material, the mixture of the KNO3 raw material and the AP material (mass ratio of 1:1), and the mixture of the potassium nitrate material coated with an inorganic-organic hybrid membrane and the AP material (mass ratio of 1:1) in Example 1 of the present invention was carried out at a relative humidity of 75% and a temperature of 25°C;

[0035] Figure 6 The moisture absorption rate-time curve of the KNO3 raw material, the inorganic-organic hybrid membrane-coated potassium nitrate material, the AP material, the mixture of the KNO3 raw material and the AP material (mass ratio 1:1), and the mixture of the inorganic-organic hybrid membrane-coated potassium nitrate material and the AP material (mass ratio 1:1) in Example 2 of the present invention was carried out at a relative humidity of 75% and a temperature of 25°C;

[0036] Figure 7 The moisture absorption rate-time curve of the KNO3 raw material, the inorganic-organic hybrid membrane-coated potassium nitrate material, the AP material, the mixture of the KNO3 raw material and the AP material (mass ratio 1:1), and the mixture of the inorganic-organic hybrid membrane-coated potassium nitrate material and the AP material (mass ratio 1:1) in Example 3 of the present invention was carried out at a relative humidity of 75% and a temperature of 25°C;

[0037] Figure 8 The moisture absorption rate-time curve of the KNO3 raw material, the potassium nitrate material coated with an inorganic-organic hybrid membrane, the AP material, the mixture of the KNO3 raw material and the AP material (mass ratio 1:1), and the mixture of the potassium nitrate material coated with an inorganic-organic hybrid membrane and the AP material (mass ratio 1:1) in Example 4 of the present invention was carried out at a relative humidity of 75% and a temperature of 25°C;

[0038] Fig. 9The moisture absorption rate-time curve of the KNO3 raw material, the potassium nitrate material coated with an inorganic-organic hybrid membrane, the AP material, the mixture of the KNO3 raw material and the AP material (mass ratio of 1:1), and the mixture of the potassium nitrate material coated with an inorganic-organic hybrid membrane and the AP material (mass ratio of 1:1) in Example 5 of the present invention was measured at a relative humidity of 75% and a temperature of 25°C. DETAILED DESCRIPTION

[0039] The present invention is further described below through specific embodiments. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the principle of the present invention, and these should also be regarded as belonging to the protection scope of the present invention.

[0040] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

[0041] The invention discloses a method for preparing a potassium nitrate material, comprising the following steps:

[0042] S1: Under room temperature, an inorganic isolating agent is placed in a reaction container and a first solvent is added, and the inorganic isolating agent is ultrasonically dispersed in the first solvent by an ultrasonic cell pulverizer, and the inorganic isolating agent is ultrasonically dispersed until the inorganic isolating agent is well dispersed (for example, after the isolation dispersion liquid I is allowed to stand for 30 minutes, no solid sedimentation occurs at the bottom of the reaction container, and the inorganic isolating agent is considered to be well dispersed), to obtain the isolation dispersion liquid I; the working mode of the ultrasonic cell pulverizer is intermittent mode, the power is 1KW, and the ultrasonic time is 5-20min;

[0043] S2: adding KNO3 and an anti-caking agent to the isolation dispersion I, heating to 30°C to 55°C, and stirring and adsorbing for 2 to 4 hours at a stirring speed of 200rpm to 400rpm, so that KNO3 fully adsorbs the isolation agent to obtain an isolation-type potassium nitrate suspension;

[0044] S3: The organic coating agent is dissolved in the second solvent to obtain a coating liquid II. Under stirring conditions, the coating liquid II is added dropwise to the isolated potassium nitrate suspension at a rate of 0.2 mL / min to 5 mL / min. While adding the coating liquid II, the temperature of the reaction system is increased to 40°C to 65°C. During the addition of the coating liquid II, the coating agent precipitates from the coating liquid II (the coating agent is dissolved in the second solvent and insoluble in the first solvent. During the addition, the coating agent will precipitate from the second solvent due to the solvent-antisolvent effect) and is coated on the surface of the KNO3 particles adsorbed with the isolation agent. After the addition is completed, the reaction is continued to be stirred at a stirring speed of 200 rpm to 400 rpm for 2 to 4 hours, followed by filtration, washing and drying to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0045] Wherein, the inorganic isolating agent is one or more of nano-hydrophobic SiO2, carbon nanotubes (CNTs), fluorinated graphene and nano-silver particles; the amount of the inorganic isolating agent added is 0.1wt% to 2wt% of the amount of KNO3 used;

[0046] The first solvent is one or more of chloroform, cyclohexane, and n-hexane; the amount of the first solvent used is 15 mL / gKNO3-30 mL / gKNO3.

[0047] The anti-caking agent is one or more of calcium phosphate, calcium carbonate, calcium silicate, titanium dioxide and aluminum silicate; the added amount of the anti-caking agent is 0.2wt% to 2wt% of the amount of KNO3.

[0048] The organic coating agent is one or more of polystyrene (PS), polyethylene oxide (PEO), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), fluororubber (F26) and polytetrafluoroethylene (PTFE); the amount of the organic coating agent added is 1wt% to 5wt% of the amount of KNO3 used;

[0049] The second solvent is one or more of toluene, xylene, ethanol, ethyl acetate, acetonitrile, and acetone; the amount of the second solvent used ranges from 5 mL to 20 mL.

[0050] The inorganic-organic hybrid membrane-coated potassium nitrate material was prepared by the preparation method of the above-mentioned potassium nitrate material, and the hygroscopicity of the KNO3 raw material, AP material and the prepared inorganic-organic hybrid membrane-coated potassium nitrate material was analyzed by the following method:

[0051] Accurately weigh about 10g of the drug pellets and place them in a weighing bottle of known mass, which is counted as m0 with an accuracy of 0.0001g. Place them in a dryer filled with a sufficient amount of saturated sodium chloride aqueous solution. Place the dryer in a 25℃ oven and control the drug pellets to be in a high temperature and high humidity environment with a relative humidity of 75% and a temperature of 25℃. Weigh the mass m of the drug pellets every 24h. i , until the difference between two consecutive weighings is no more than 0.0002g. The hygroscopicity of the drug particles is calculated as follows:

[0052]

[0053] Where W i is the hygroscopicity of the drug particles; m i is the mass of the granules and weighing bottle at the i-th weighing, g; m0 is the initial mass of the granules and weighing bottle, g; m is the mass of the granules, g.

[0054] Example 1

[0055] Step 1: Weigh 0.1 g of nano-hydrophobic SiO2 and place it in a 600 ml beaker, accurately measure 350 ml of cyclohexane, and ultrasonicate it with an ultrasonic cell crusher at 1 KW ultrasonic power for 8 minutes, then transfer it to a 500 ml three-necked flask for standby use, which is the isolation dispersion I;

[0056] Step 2: Weigh 20g KNO3 and 0.15g titanium dioxide and add them to the isolated dispersion liquid I, raise the temperature to 50°C, set the stirring speed to 300rpm, and stir the reaction for 3h to obtain an isolated anti-hygroscopic potassium nitrate suspension;

[0057] Step 3: Weigh 0.5g F26 and dissolve it in 20ml toluene to obtain coating liquid II; add the coating liquid II dropwise into the isolated anti-hygroscopic potassium nitrate suspension at a dropping speed of 0.5ml / min, raise the temperature to 60°C, maintain the stirring speed at 300rpm, stir and react for 4h, filter, wash and dry after the reaction is completed to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0058] The KNO3 raw material was tested by SEM and EDS, and the results are shown in Figure 1 SEM images and Figure 2 EDS spectrum of Figure 1 It can be seen that the KNO3 raw material particles are irregular in shape and have a rough surface. Figure 2 From the EDS spectrum, we can see that K, N and O elements are evenly distributed on the surface of KNO3 raw material particles, and the element proportions are close to the theoretical values.

[0059] The prepared inorganic-organic hybrid membrane coated potassium nitrate material was tested by SEM and EDS. Figure 3 SEM images and Figure 4 EDS spectrum of Figure 3 It can be seen that the surface of the potassium nitrate material coated with the inorganic-organic hybrid membrane is smoother than that of the raw material, and there are a few wrinkles, indicating that the hybrid membrane is successfully formed; Figure 4 It can be seen that in addition to K, N, and O elements, Si, F, and C elements are evenly distributed on the surface of the KNO3 material particles coated with the inorganic-organic hybrid membrane, indicating the successful adsorption of nano-hydrophobic SiO2 and the successful coating of the coating agent F26, as well as the successful preparation of potassium nitrate materials coated with inorganic-organic hybrid membranes.

[0060] 10g KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of potassium nitrate material and AP material coated with inorganic-organic hybrid membrane (mass ratio 1:1) were weighed respectively, and the hygroscopicity test was carried out under the conditions of relative humidity 75% and temperature 25°C. The moisture absorption rate-time curves of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of potassium nitrate material and AP material coated with inorganic-organic hybrid membrane (mass ratio 1:1) are as shown in FIG. Figure 5 As shown by Figure 5 It can be seen that the saturated moisture absorption rate of KNO3 raw material is -0.1482%, the saturated moisture absorption rate of potassium nitrate material coated with inorganic-organic hybrid membrane is -0.0287% (the saturated moisture absorption rates of KNO3 raw material and potassium nitrate material coated with inorganic-organic hybrid membrane are both less than 0, which means that both are not hygroscopic), the saturated moisture absorption rate of AP material is 0.0541%, the saturated moisture absorption rate of the mixture of KNO3 raw material and AP material (mass ratio 1:1) is 17.328%, and the saturated moisture absorption rate of the mixture of potassium nitrate material coated with inorganic-organic hybrid membrane and AP material (mass ratio 1:1) is 0.4043%.

[0061] Example 2

[0062] Step 1: Weigh 0.05 g of nanosilver particles and place them in a 600 ml beaker, accurately measure 350 ml of n-hexane, ultrasonicate them with an ultrasonic cell crusher at 1 kW ultrasonic power for 10 min, and then transfer them to a 500 ml three-necked flask for standby use, which is the isolation dispersion I;

[0063] Step 2: Weigh 20g KNO3 and 0.3g calcium phosphate and add them to the isolated dispersion liquid I, raise the temperature to 40°C, set the stirring speed to 300rpm, and stir the reaction for 3h to obtain an isolated anti-hygroscopic potassium nitrate suspension;

[0064] Step 3: Weigh 1 g of PS and dissolve it in 10 ml of acetone to obtain coating liquid II; add the coating liquid II dropwise into the isolated anti-hygroscopic potassium nitrate suspension at a dropping speed of 0.2 ml / min, while raising the temperature to 55°C, maintaining the stirring speed at 300 rpm, stirring the reaction for 3 hours, and filtering, washing, and drying after the reaction is completed to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0065] Weigh 10g of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1). Perform a hygroscopicity test at a relative humidity of 75% and a temperature of 25°C. The moisture absorption rate-time curves of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1) are as shown in FIG. Figure 6 As shown by Figure 6 It can be seen that the saturated moisture absorption rate of KNO3 raw material is 0.0021%, the saturated moisture absorption rate of potassium nitrate material coated with inorganic-organic hybrid membrane is -0.0012%, the saturated moisture absorption rate of AP material is 0.0524%, the saturated moisture absorption rate of the mixture of KNO3 raw material and AP material (mass ratio 1:1) is 17.1689%, and the saturated moisture absorption rate of the mixture of potassium nitrate material coated with inorganic-organic hybrid membrane and AP material (mass ratio 1:1) is 0.6521%.

[0066] Example 3

[0067] Step 1: Weigh 0.2 g of CNTs and place them in a 600 ml beaker, accurately measure 350 ml of cyclohexane, and ultrasonicate them using an ultrasonic cell crusher at 1 KW ultrasonic power for 5 min, then transfer them to a 500 ml three-necked flask for standby use, which is the isolation dispersion I;

[0068] Step 2: Weigh 20g KNO3 and 0.2g aluminum silicate and add them to the isolated dispersion liquid I, raise the temperature to 40°C, set the stirring speed to 200rpm, and stir the reaction for 4h to obtain an isolated anti-hygroscopic potassium nitrate suspension;

[0069] Step 3: Weigh 0.3g PMMA and dissolve it in 15ml ethyl acetate to obtain coating liquid II; add the coating liquid II dropwise into the isolated anti-hygroscopic potassium nitrate suspension at a dropping speed of 0.5ml / min, raise the temperature to 55°C, maintain the stirring speed at 300rpm, stir the reaction for 2.5h, filter, wash and dry after the reaction is completed to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0070] Weigh 10g of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1). Perform a hygroscopicity test at a relative humidity of 75% and a temperature of 25°C. The moisture absorption rate-time curves of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1) are as shown in FIG. Figure 7 As shown by Figure 7 It can be seen that the saturated moisture absorption rate of KNO3 raw material is 0%, the saturated moisture absorption rate of potassium nitrate material coated with inorganic-organic hybrid membrane is -0.011%, the saturated moisture absorption rate of AP material is 0.0492%, the saturated moisture absorption rate of the mixture of KNO3 raw material and AP material (mass ratio 1:1) is 16.985%, and the saturated moisture absorption rate of the mixture of potassium nitrate material coated with inorganic-organic hybrid membrane and AP material (mass ratio 1:1) is 2.3410%.

[0071] Example 4

[0072] Step 1: Weigh 0.4 g of fluorinated graphene and place it in a 600 ml beaker, accurately measure 350 ml of cyclohexane, and ultrasonicate it with an ultrasonic cell crusher at 1 KW ultrasonic power for 18 minutes, then transfer it to a 500 ml three-necked flask for standby use, which is the isolation dispersion I;

[0073] Step 2: Weigh 20g KNO3 and 0.3g calcium carbonate and add them to the isolated dispersion liquid I, raise the temperature to 35°C, set the stirring speed to 400rpm, and stir the reaction for 4h to obtain an isolated anti-hygroscopic potassium nitrate suspension;

[0074] Step 3: Weigh 1g PEO and dissolve it in 25ml ethanol to obtain coating liquid II; add the coating liquid II dropwise into the isolated anti-hygroscopic potassium nitrate suspension at a dropping speed of 1ml / min, raise the temperature to 65°C, maintain the stirring speed at 300rpm, and stir the reaction for 3h. After the reaction is completed, filter, wash, and dry to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0075] Weigh 10g of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1). Perform a hygroscopicity test at a relative humidity of 75% and a temperature of 25°C. The moisture absorption rate-time curves of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1) are as shown in FIG. Figure 8 As shown by Figure 8 It can be seen that the saturated moisture absorption rate of KNO3 raw material is -0.0199%, the saturated moisture absorption rate of potassium nitrate material coated with inorganic-organic hybrid membrane is -0.0089% (the saturated moisture absorption rates of KNO3 raw material and potassium nitrate material coated with inorganic-organic hybrid membrane are both less than 0, indicating that both are non-hygroscopic), the saturated moisture absorption rate of AP material is 0.0602%, the saturated moisture absorption rate of the mixture of KNO3 raw material and AP material (mass ratio 1:1) is 16.723%, and the saturated moisture absorption rate of the mixture of potassium nitrate material coated with inorganic-organic hybrid membrane and AP material (mass ratio 1:1) is 0.3044%.

[0076] Example 5

[0077] Step 1: Weigh 0.2 g of CNTs and place them in a 600 ml beaker, accurately measure 350 ml of cyclohexane, and ultrasonicate them using an ultrasonic cell crusher at 1 KW ultrasonic power for 10 min, then transfer them to a 500 ml three-necked flask for standby use, which is the isolation dispersion I;

[0078] Step 2: Weigh 20g KNO3 and 0.3g calcium silicate and add them to the isolated dispersion liquid I, raise the temperature to 50°C, set the stirring speed to 300rpm, and stir the reaction for 4h to obtain an isolated anti-hygroscopic potassium nitrate suspension;

[0079] Step 3: Weigh 1g of PMMA and dissolve it in 30ml of xylene to obtain coating liquid II; add the coating liquid II dropwise into the isolated anti-hygroscopic potassium nitrate suspension at a dropping speed of 2ml / min, raise the temperature to 60°C, maintain the stirring speed at 300rpm, and stir the reaction for 3h. After the reaction is completed, filter, wash, and dry to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

[0080] Weigh 10g of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1). Perform a hygroscopicity test at a relative humidity of 75% and a temperature of 25°C. The moisture absorption rate-time curves of KNO3 raw material, inorganic-organic hybrid membrane coated potassium nitrate material, AP material, a mixture of KNO3 raw material and AP material (mass ratio 1:1), and a mixture of inorganic-organic hybrid membrane coated potassium nitrate material and AP material (mass ratio 1:1) are as shown in FIG. Fig. 9 As shown by Fig. 9 It can be seen that the saturated moisture absorption rate of KNO3 raw material is 0.0012%, the saturated moisture absorption rate of potassium nitrate material coated with inorganic-organic hybrid membrane is -0.0032%, the saturated moisture absorption rate of AP material is 0.0480%, the saturated moisture absorption rate of the mixture of KNO3 raw material and AP material (mass ratio 1:1) is 17.682%, and the saturated moisture absorption rate of the mixture of potassium nitrate material coated with inorganic-organic hybrid membrane and AP material (mass ratio 1:1) is 3.2010%.

[0081] The present invention is described in detail above in combination with specific implementation methods and exemplary examples. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments; the above description cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, the technical solution of the present invention and its implementation methods may be subjected to a variety of equivalent substitutions, modifications or improvements, all of which fall within the scope of the present invention; the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a potassium nitrate material, characterized in that: The following steps are involved: S1: placing an inorganic isolating agent in a reaction container and adding a first solvent, and ultrasonically dispersing the inorganic isolating agent to obtain an isolating dispersion; the inorganic isolating agent is one or more of nano-hydrophobic SiO2, carbon nanotubes, fluorinated graphene and nano-silver particles; S2: adding KNO3 and an anti-caking agent to the isolated dispersion, heating, stirring, and adsorbing to obtain an isolated potassium nitrate suspension; S3: dissolving the organic coating agent in the second solvent to obtain a coating liquid, and dropping the coating liquid into the isolated potassium nitrate suspension under stirring conditions, while increasing the temperature of the reaction system while dropping the coating liquid, and continuing to stir the reaction after the dropping is completed, followed by filtering, washing, and drying to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

2. The method for preparing potassium nitrate material according to claim 1, wherein The addition amount of the inorganic isolation agent is 0.1wt% to 2wt% of the amount of KNO3.

3. The method for preparing potassium nitrate material according to claim 1, characterized in that: The anti-caking agent is one or more of calcium phosphate, calcium carbonate, calcium silicate, titanium dioxide and aluminum silicate; the added amount of the anti-caking agent is 0.2wt% to 2wt% of the amount of KNO3.

4. The method for preparing potassium nitrate material according to claim 1, characterized in that: The organic coating agent is one or more of polystyrene, polyethylene oxide, polyethylene terephthalate, polymethyl methacrylate, fluororubber and polytetrafluoroethylene; the added amount of the organic coating agent is 1wt% to 5wt% of the amount of KNO3 used.

5. The method for preparing potassium nitrate material according to claim 1, characterized in that: The first solvent is one or more of chloroform, cyclohexane, and n-hexane; the amount of the first solvent is 15 mL / gKNO3-30 mL / gKNO3; The second solvent is one or more of toluene, xylene, ethanol, ethyl acetate, acetonitrile, and acetone; the amount of the second solvent used ranges from 5 mL to 20 mL.

6. The method for preparing potassium nitrate material according to claim 1, characterized in that: The step S1 comprises: Under room temperature conditions, an inorganic isolating agent is placed in a reaction container and a first solvent is added, and the inorganic isolating agent is ultrasonically dispersed in the first solvent by an ultrasonic cell pulverizer to obtain an isolated dispersion liquid; the working mode of the ultrasonic cell pulverizer is an intermittent mode, the power is 1KW, and the ultrasonic time is 5-20min.

7. The method for preparing potassium nitrate material according to claim 1, characterized in that: The step S2 comprises: Add KNO3 and an anti-caking agent to the isolated dispersion, heat to 30°C to 55°C, and stir and adsorb at a stirring speed of 200rpm to 400rpm for 2 to 4 hours to obtain an isolated potassium nitrate suspension.

8. The method for preparing potassium nitrate material according to claim 1, characterized in that: The step S3 comprises: The organic coating agent is dissolved in the second solvent to obtain a coating liquid, and the coating liquid is added dropwise to the isolated potassium nitrate suspension at a rate of 0.2 mL / min to 5 mL / min under stirring. While adding the coating liquid II, the temperature of the reaction system is increased to 40°C to 65°C. After the addition is completed, the reaction is continued to be stirred at a stirring speed of 200 rpm to 400 rpm for 2 to 4 hours, followed by filtering, washing and drying to obtain an inorganic-organic hybrid membrane-coated potassium nitrate material.

9. A potassium nitrate material coated with an inorganic-organic hybrid membrane prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the inorganic-organic hybrid membrane-coated potassium nitrate material as claimed in claim 9 in the preparation of propellants, explosives or other energetic materials.

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