Propellant powder, preparation method thereof and powder particle surface modification method

Abstract

The preparation method of the propellant powder comprises the following steps: weighing propellant powder particles, and adding the propellant powder particles into a buffer solution of tris (hydroxymethyl) aminomethane under continuous magnetic stirring to obtain a mixed solution I; weighing dopamine hydrochloride particles, pouring the dopamine hydrochloride particles into the mixed solution I, and dissolving to form a mixed solution II; the second mixed solution is continuously stirred to induce in-situ polymerization of dopamine hydrochloride on the surfaces of propellant particles, and polydopamine-coated propellant is formed; washing the polydopamine coated propellant, and drying the polydopamine coated propellant to remove the residual solvent on the surface; putting the propellant powder into a coating chamber of fluidized bed equipment, and fully fluidizing; and conveying the water-based coating liquid for the propellant into a spray gun in a fluidized bed coating chamber, and continuously spraying to obtain the water-based coated propellant. A polydopamine coating layer is generated on the surface of the propellant in situ through a self-polymerization reaction, the roughness of the surfaces of propellant particles is effectively improved, the hydrophilicity and the chemical reaction activity are improved, good coating of a subsequent water-based coating system on the surfaces of the propellant particles is achieved, and the product effect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials. Background Art

[0002] Propellant is the main power source for the launch of barreled weapons and an indispensable strategic resource for maintaining national defense security. It releases chemical energy to do external work by burning. Granular small-sized propellant has the characteristics of good dispersibility, high filling density, and low production cost. It is one of the main charges for small-caliber barreled weapons. In order to realize the incremental characteristics of its energy release and enhance the comprehensive application performance of barreled weapons, domestic and foreign researchers have conducted a lot of research.

[0003] Coated propellant technology is to form one or more layers of thin films with a low burning rate on the surface of the propellant through processes such as spraying, and to control the composition and structure of different coating layers so that the burning rate of the propellant increases layer by layer from the surface to the inside in the normal direction. Coated propellant technology has the advantages of simple operation, strong applicability, and good product consistency. It has become the main way to adjust the combustion performance of large-sized propellants such as 7-hole, 19-hole and 37-hole propellants. It has the ability to achieve the gradual release of energy of the matrix propellant, delay ignition and regulate the temperature coefficient of the burning rate. Zhang Lina compounded triguanide-15 absorption tablets and titanium dioxide in an alcohol-ketone solvent as a coating agent, and coated them in double layers on the surface of the superporous nitroguanidine propellant, which effectively improved the gradual release of energy of the propellant. In addition, Zheng Qilong and others used the "premixing-spraying-curing" process to achieve the coating of polyazide glycidyl ether-based polyurethane on the surface of 4 / 7 single-base propellant with a rotary drum coating device. However, the organic solvent system has the following limitations: (1) Organic solvents and their volatile gases are easy to burn; (2) They are irritating and toxic to a certain extent, and long-term use can easily cause serious harm to the environment and the health of operators; (3) The coating liquid has high viscosity, which can easily cause equipment blockage during coating, increasing the difficulty and cost of post-processing; (4) It is easy to damage the coating matrix, causing the surface of the propellant particles to plasticize or even partially dissolve, aggravating the adhesion and agglomeration phenomenon (especially for small-particle propellants). At the same time, the organic solvent that penetrates into the interior of the particles also increases the difficulty of subsequent drying.

[0004] The aqueous coating system uses water as the dispersion medium, and the polymer is dispersed in the aqueous phase in the form of dissolved molecular chains or particles. Compared with the solvent-based coating system, the polymer aqueous dispersion has a high solid content, low viscosity, environmental friendliness, safety in use, low cost, and will not damage the propellant matrix. However, the surface of granular propellants is dense and smooth, with a low content of reactive groups and poor surface hydrophilicity, so it is difficult to be well wetted by the aqueous coating system. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a propellant, which adopts an in-situ self-polymerization non-destructive coating measure based on the method of improving the surface reactivity of granular propellants by biological self-polymerization, so that the propellant particles have good surface reactivity and hydrophilicity while maintaining the original physical and chemical structure, and effectively improve the coating effectiveness of the aqueous coating system on the propellant surface.

[0006] The technical solution adopted in this application is: a method for preparing a propellant, the steps are as follows: 1) Preparation of a mixed solution of propellant particles: accurately weigh a certain mass of propellant particles, add them into a container A (100 mL beaker) containing a buffer solution of tris(hydroxymethyl)aminomethane under continuous magnetic stirring, so that the particles are completely stirred to obtain a mixed solution 1; 2) Preparation of dopamine solution: accurately weigh a certain amount of dopamine hydrochloride particles, pour them into mixed solution 1 under continuous magnetic stirring, and completely dissolve them to form mixed solution 2; 3) Surface modification of propellant particles: Place the mixed solution 2 in a magnetic stirrer and stir continuously for a certain period of time at a certain temperature to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; 4) Cleaning and drying of propellant particles: the polydopamine-coated propellant is rinsed alternately with deionized water and anhydrous ethanol for multiple times, and then placed in an oven for drying to drive off residual solvent on the surface; 5) Fluidization of propellant particles: Place 5-10 g of the propellant obtained in step 4) in the coating chamber of the fluidized bed equipment and set the fluidization wind speed to 10-12 m s -1 , fluidization temperature is 40~50℃, turn on the anti-static rod to make the propellant particles fully fluidized in the coating chamber; 6) Propellant coating: The aqueous coating liquid for the propellant is transported to the spray gun in the fluidized bed coating chamber and sprayed continuously for 5 to 30 minutes to obtain the aqueous coated propellant.

[0007] Step 6) is specifically as follows: insert the feed pipe in the fluidized bed into the aqueous coating liquid for the propellant, set the peristaltic pump speed to 0.9-1.09 rpm, and deliver the coating liquid to the spray gun in the fluidized bed coating chamber. The atomization pressure of the spray gun is 8-10 psi, and the spraying is continued for 5-30 minutes.

[0008] In step 1), the propellant particles are spherical, oblate, or seven-hole in shape, and have a mass of less than 5 g.

[0009] In step 1), the concentration of the buffer solution of tris(hydroxymethyl)aminomethane is 10±0.5 mM and the pH is 8.5±0.1.

[0010] The concentration of dopamine hydrochloride in the second mixed solution is 1-5 mg / mL.

[0011] In step 3), the reaction temperature is 25±2°C, the reaction time is 24±0.5h, and the magnetic stirring speed is 500±50r / min.

[0012] In step 4), deionized water and anhydrous ethanol are used for rinsing 3 times each, the drying temperature is 55±3°C, and the drying time is 24±1h.

[0013] The method also includes step 7) drying the coated propellant: placing the coated propellant particles obtained in step 6) in a water bath oven at 50-60° C. and drying for 36-48 hours to drive off the residual moisture inside the coating.

[0014] Another aspect of the present invention provides a propellant, comprising a drug particle, an interface layer coated outside the drug particle, and an aqueous coating coated outside the interface layer; the interface layer is a polydopamine coating layer formed by in-situ polymerization of dopamine hydrochloride on the surface of the drug particle.

[0015] On the other hand, the present invention provides a method for modifying the surface of propellant particles. First, the propellant particles are uniformly dispersed in a tris(hydroxymethyl)aminomethane buffer solution containing a certain concentration of dopamine hydrochloride under continuous magnetic stirring. Finally, continuous stirring is performed at a certain temperature for a certain period of time to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant, thereby achieving non-destructive modification of the surface of the propellant particles.

[0016] The specific steps of the surface modification method of propellant particles provided by the present invention are as follows: 1) Preparation of a mixed solution of propellant particles: accurately weigh a certain mass of propellant particles, add them into a container A (100 mL beaker) containing a buffer solution of tris(hydroxymethyl)aminomethane under continuous magnetic stirring, so that the particles are completely stirred to obtain a mixed solution 1; 2) Preparation of dopamine solution: accurately weigh a certain amount of dopamine hydrochloride particles, pour them into mixed solution 1 under continuous magnetic stirring, and completely dissolve them to form mixed solution 2; 3) Surface modification of propellant particles: Place the mixed solution 2 in a magnetic stirrer and stir continuously for a certain period of time at a certain temperature to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; 4) Cleaning and drying of propellant particles: The polydopamine-coated propellant is rinsed alternately with deionized water and anhydrous ethanol for multiple times, and then placed in an oven for drying to remove residual solvent on the surface.

[0017] The surface modification method of propellant particles provided by the present invention is based on improving the surface reactivity of granular propellants by bio-autopolymerization, using dopamine as a reaction monomer, and generating a polydopamine coating layer in situ on the surface of the propellant through autopolymerization under weakly alkaline conditions. The entire reaction process is carried out in an aqueous phase, with high coating efficiency, and is suitable for surface modification of propellant particles of different sizes and different components. The surface of the propellant particles after coating has a high roughness and hydroxyl content, has good reactivity and hydrophilicity, and can effectively improve the surface coating effect of the aqueous coating system.

[0018] The coating system and solvent of the present invention are polydopamine and deionized water respectively, which are environmentally friendly and low in cost. At the same time, the coating process is based on in-situ self-polymerization, which is simple to operate and has good reproducibility, and will not cause damage to the medicine particles. It can be used for propellant medicine particles of different sizes and different components. The generated polydopamine coating layer can effectively increase the roughness of the surface of the propellant medicine particles, improve the hydrophilicity and chemical reaction activity, and realize good coating of the subsequent aqueous coating system on the surface of the medicine particles, and the product effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The surface microscopic morphology of propellant particles obtained by using dopamine solutions with different concentrations; Figure 2 The infrared spectra and Raman spectra of propellant particles obtained using dopamine solutions with different concentrations. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without carrying out creative work are within the scope of protection of the present invention.

[0021] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0022] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0023] Example 1: Modification of propellant particles using a dopamine solution with a concentration of 1 mg / mL (1) Accurately weigh 1 g of propellant particles and add them into a 100 mL beaker containing 50 mL of tris(hydroxymethylaminomethane) buffer solution (10 mM, pH = 8.5) under magnetic stirring at 250 rpm / min. Stir for 10 min to completely agitate the particles. (2) Accurately weigh 50 mg of dopamine hydrochloride particles, pour them into the propellant mixed solution obtained in step 1 under magnetic stirring at 250 r / min, and continue stirring for 10 min to completely dissolve them to form a mixed solution; (3) placing the mixed solution obtained in step 2 in a magnetic stirrer and stirring continuously at 25°C for 24 h to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; (4) The polydopamine-coated propellant obtained in step 3 was rinsed with deionized water and anhydrous ethanol three times each, and then placed in an oven at 50°C for 36 h to drive off the residual solvent on the surface.

[0024] The microscopic morphology of the drug particles obtained in step 4 was observed by scanning electron microscopy. Figure 1 As shown in the figure with 1 mg / mL, compared with the untreated propellant, a small amount of polydopamine clusters appeared on its surface, and the roughness increased. The Fourier transform infrared spectroscopy and microscopic confocal Raman spectrometer were used to test the drug particles. The Fourier transform infrared spectrum and Raman spectrum test results showed that ( Figure 2 ), the hydroxyl peak intensity on the surface of the modified propellant particles increased, and the reaction activity and hydrophilicity increased.

[0025] (5) Turn on the fluidized bed equipment, place 10 g of coated granules in the coating chamber, and set the fluidization wind speed to 12 m s -1 , fluidization temperature 50℃, turn on the anti-static rod to make the particles fully fluidized in the coating chamber.

[0026] (6) Insert the feed tube into the aqueous coating system, set the peristaltic pump speed to 1.09 rpm, the atomization pressure of the spray gun to 10 psi, and continue spraying for 15 min to obtain an aqueous coated propellant.

[0027] (7) The coated pellets were placed in a water bath oven at 55°C and dried for 48 hours to remove the residual moisture inside the coating. The water-based coated propellant was taken out and sealed for storage. The mass fraction of the water-based coating of the obtained propellant increased from 0.5% when it was not modified to 3%.

[0028] Example 2: Modification of propellant particles using a dopamine solution with a concentration of 3 mg / mL (1) Accurately weigh 1 g of propellant particles and add them into a 100 mL beaker containing 50 mL of tris(hydroxymethyl)aminomethane buffer solution (10 mM, pH = 8.5) under magnetic stirring at 250 r / min. Stir for 10 min to completely agitate the particles. (2) Accurately weigh 150 mg of dopamine hydrochloride particles, pour them into the propellant mixed solution obtained in step 1 under magnetic stirring at a speed of 300 r / min, and continue stirring for 15 min to completely dissolve them to form a mixed solution; (3) placing the mixed solution obtained in step 2 in a magnetic stirrer and stirring continuously at 25°C for 24 h to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; (4) The polydopamine-coated propellant obtained in step 3 was rinsed with deionized water and anhydrous ethanol three times each, and then placed in an oven at 55°C for 30 h to drive off the residual solvent on the surface.

[0029] The microscopic morphology of the drug particles obtained in step 4 is as follows Figure 1 As shown in the figure marked with 1 mg / mL, compared with the untreated propellant, a small amount of polydopamine clusters appeared on its surface, and the roughness increased; the Fourier transform infrared spectroscopy and Raman spectroscopy test results showed that ( Figure 2 ), the hydroxyl peak intensity on the surface of the modified propellant particles increased, and the reaction activity and hydrophilicity increased.

[0030] (5) Turn on the fluidized bed equipment, place 10 g of coated granules in the coating chamber, set the fluidization wind speed to 12 m s-1, the fluidization temperature to 50 °C, turn on the anti-static rod, and allow the granules to be fully fluidized in the coating chamber.

[0031] (6) Insert the feed tube into the aqueous coating system, set the peristaltic pump speed to 1.09 rpm, the spray gun atomization pressure to 10 psi, and continue spraying for 15 min to obtain aqueous coated propellant.

[0032] (7) The coated pellets were placed in a water bath oven at 55°C and dried for 48 hours to remove the residual moisture inside the coating. The water-based coated propellant was taken out and sealed for storage. The mass fraction of the water-based coating of the obtained propellant increased from 0.5% when it was not modified to 5%.

[0033] Example 3: Modification of propellant particles using a dopamine solution with a concentration of 5 mg / mL (1) Accurately weigh 1 g of propellant particles and add them into a 100 mL beaker containing 50 mL of tris(hydroxymethyl)aminomethane buffer solution (10 mM, pH = 8.5) under magnetic stirring at 250 r / min. Stir for 10 min to completely agitate the particles. (2) Accurately weigh 250 mg of dopamine hydrochloride particles, pour them into the propellant mixed solution obtained in step 1 under magnetic stirring at a speed of 400 r / min, and continue stirring for 20 min to completely dissolve them to form a mixed solution; (3) placing the mixed solution obtained in step 2 in a magnetic stirrer and stirring continuously at 25°C for 24 h to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; (4) The polydopamine-coated propellant obtained in step 3 was rinsed with deionized water and anhydrous ethanol three times each, and then placed in an oven at 60°C for 24 h to drive off the residual solvent on the surface.

[0034] The microscopic morphology of the drug particles obtained in step 4 is as follows Figure 1 As shown in the figure marked with 1 mg / mL, compared with the untreated propellant, a small amount of polydopamine clusters appeared on its surface, and the roughness increased; the Fourier transform infrared spectroscopy and Raman spectroscopy test results showed that ( Figure 2 ), the hydroxyl peak intensity on the surface of the modified propellant particles increased, and the reaction activity and hydrophilicity increased.

[0035] (5) Turn on the fluidized bed equipment, place 10 g of coated granules in the coating chamber, and set the fluidization wind speed to 12 m s -1 , fluidization temperature 50℃, turn on the anti-static rod to make the particles fully fluidized in the coating chamber.

[0036] (6) Insert the feed tube into the aqueous coating system, set the peristaltic pump speed to 1.09 rpm, the spray gun atomization pressure to 10 psi, and continue spraying for 15 min to obtain aqueous coated propellant.

[0037] (7) The coated pellets were placed in a water bath oven at 55°C and dried for 48 hours to remove the residual moisture inside the coating. The water-based coated propellant was taken out and sealed for storage. The mass fraction of the water-based coating of the obtained propellant increased from 0.5% when it was not modified to 7%.

[0038] The above description is only an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a propellant, characterized in that: Here are the steps: 1) Preparation of a mixed solution of propellant particles: Weigh a certain mass of propellant particles, add them into a container A containing a buffer solution of tris(hydroxymethyl)aminomethane under continuous magnetic stirring, so that the particles are completely stirred to obtain a mixed solution 1; 2) Preparation of dopamine solution: Weigh a certain amount of dopamine hydrochloride particles, pour them into mixed solution 1 under continuous magnetic stirring, and completely dissolve them to form mixed solution 2; 3) Surface modification of propellant particles: Mixed solution 2 is continuously stirred at a certain temperature for a certain period of time to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; 4) Cleaning and drying of propellant particles: the polydopamine-coated propellant is rinsed alternately with deionized water and anhydrous ethanol for multiple times, and then dried to remove residual solvent on the surface; 5) Fluidization of propellant particles: placing the propellant obtained in step 4) in a coating chamber of a fluidized bed equipment, so that the propellant particles are fully fluidized in the coating chamber; 6) Propellant coating: The aqueous coating liquid for the propellant is transported to the spray gun in the fluidized bed coating chamber and sprayed continuously for a certain period of time to obtain the aqueous coated propellant.

2. The method for preparing a propellant according to claim 1, characterized in that: In step 1), the propellant particles are spherical, oblate, or seven-hole in shape, and have a mass of less than 5 g.

3. The method for preparing propellant according to claim 1, characterized in that: In step 1), the concentration of the buffer solution of tris(hydroxymethyl)aminomethane is 10±0.5 mM and the pH is 8.5±0.

1.

4. The method for preparing propellant according to claim 1, characterized in that: The concentration of dopamine hydrochloride in the second mixed solution is 1-5 mg / mL.

5. The method for preparing propellant according to claim 1, characterized in that: In step 3), the reaction temperature is 25±2°C, the reaction time is 24±0.5h, and the magnetic stirring speed is 500±50r / min.

6. The method for preparing propellant according to claim 1, characterized in that: In step 4), deionized water and anhydrous ethanol are used for rinsing 3 times each, the drying temperature is 55±3°C, and the drying time is 24±1h.

7. The method for preparing propellant according to claim 1, characterized in that: The method also includes step 7) drying the coated propellant: placing the coated propellant particles obtained in step 6) in a water bath oven at 50-60° C. and drying for 36-48 hours to drive off the residual moisture inside the coating.

8. A propellant, characterized in that: The invention comprises a drug particle, an interface layer coated on the outside of the drug particle, and an aqueous coating coated on the outside of the interface layer; the interface layer is a polydopamine coating layer formed by in-situ polymerization of dopamine hydrochloride on the surface of the drug particle.

9. A method for modifying the surface of a propellant particle, characterized in that: Firstly, the propellant particles are uniformly dispersed in a tris(hydroxymethylaminomethane) buffer solution containing a certain concentration of dopamine hydrochloride under continuous magnetic stirring. Finally, continuous stirring is carried out at a certain temperature for a certain period of time to induce the in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form polydopamine-coated propellant, thereby achieving non-destructive modification of the surface of the propellant particles.

10. The method for modifying the surface of propellant particles according to claim 9, characterized in that: The specific steps are as follows: 1) Preparation of a mixed solution of propellant particles: accurately weigh a certain mass of propellant particles, add them into a container A containing a buffer solution of tris(hydroxymethyl)aminomethane under continuous magnetic stirring, so that the particles are completely stirred to obtain a mixed solution 1; 2) Preparation of dopamine solution: accurately weigh a certain amount of dopamine hydrochloride particles, pour them into mixed solution 1 under continuous magnetic stirring, and completely dissolve them to form mixed solution 2; 3) Surface modification of propellant particles: Mixed solution 2 is continuously stirred at a certain temperature for a certain period of time to induce in-situ polymerization of dopamine hydrochloride on the surface of the propellant particles to form a polydopamine-coated propellant; 4) Cleaning and drying of propellant particles: The polydopamine-coated propellant is rinsed alternately with deionized water and anhydrous ethanol for multiple times, and then dried to remove residual solvent on the surface.

Images