Polyamide type solid propellant slurry viscosity-reducing auxiliary agent and preparation method thereof

Abstract

The invention discloses a multifunctional polyamide type solid propellant slurry viscosity reduction auxiliary agent and a preparation method, and belongs to the field of viscosity reduction auxiliary agents, dimer acid and a polyamine compound are subjected to a condensation reaction at 135-150 DEG C, and a polyamide prepolymer is generated in obtained reaction liquid; and cooling the reaction liquid, adding a solvent, uniformly mixing, adding a vinyl monomer at 45-60 DEG C, reacting, and finally cooling to room temperature to obtain the multifunctional polyamide type solid propellant slurry viscosity-reducing auxiliary agent. According to the present invention, the use amounts of the dimer acid, the polyamine compound and the vinyl monomer are respectively 47-67%, 18-44% and 9-25% by mass, such that the fluidity and the viscosity in the propellant slurry can be effectively improved, and the mechanical strength of the cured product can be improved;

Description

TECHNICAL FIELD

[0001] The application belongs to the field of viscosity reducing additives, and particularly relates to a polyamide type solid propellant slurry viscosity reducing additive and a preparation method. BACKGROUND

[0002] A solid propellant is a solid mixture composed of oxidizers, fuels (combustible agents) and other additives. The preparation process of the solid propellant mainly includes three major links of slurry mixing, pouring and curing. Among them, the viscosity of the slurry directly affects the mixing uniformity, the pouring forming quality and the performance stability of the final propellant.

[0003] With the continuous development of high solid content and high filling propellant formulations, the overall viscosity of the system is significantly increased, which leads to the decrease of slurry fluidity, the increase of mixing energy consumption, the difficulty of flow leveling, and even the process defects such as air bubble entrainment and filling deficiency, which seriously restricts the forming quality and production efficiency of the propellant. Therefore, the development of a special process additive which can effectively reduce the viscosity of the system and improve the flow characteristics is a key technical problem to be solved at present.

[0004] At present, the processing additives for reducing the viscosity of the solid propellant slurry are mostly inert organic solvents or low molecular plasticizers, which can reduce the viscosity of the system in the short term through dilution effect, but often have problems such as large evaporation, volatile pollution or poor compatibility with the system. Some of them also affect the thermal stability and storage life of the propellant. In addition, some additives containing lubricating structures have no obvious improvement in fluidity at high temperature, and have strong migration in the system, which can easily cause phase separation or weak mechanical interface, and reduce the long-term performance of the propellant. Therefore, it is urgent to develop a multifunctional viscosity reducing additive with good thermal stability, high structural compatibility and the ability to significantly improve the viscosity of the solid propellant slurry. SUMMARY

[0005] In view of the problems in the prior art, the application provides a polyamide type solid propellant slurry viscosity reducing additive and a preparation method, so as to develop a multifunctional viscosity reducing additive with good thermal stability, high structural compatibility and the ability to significantly improve the viscosity of the solid propellant slurry, which can effectively improve the fluidity and reduce the viscosity of the propellant slurry, and at the same time improve the mechanical strength of the product after curing.

[0006] The application is realized by the following technical scheme:

[0007] A preparation method of a polyamide type solid propellant slurry viscosity reducing additive, comprising the following steps:

[0008] S1, condensing a dimer acid and a polyamine compound at 135-150 DEG C to obtain a polyamide prepolymer in the reaction liquid;

[0009] S2, after the reaction liquid is cooled, a solvent is added and mixed uniformly, then the vinyl monomer is added and reacted at 45-60 DEG C, and finally the temperature is reduced to room temperature to obtain the multifunctional polyamide type solid propellant slurry viscosity reducer;

[0010] The dimer acid, the polyamine compound and the vinyl monomer are used in amounts of 47-67%, 18-44% and 9-25% by mass percentage respectively.

[0011] The further improvement of the present application is that:

[0012] In the dimer acid in S1, the content of the dimer is greater than 98%. The polyamine compound is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine. The dimer acid and the polyamine compound are condensed and reacted at 135-150 DEG C for 4-5 h to obtain a polyamide prepolymer in the reaction liquid.

[0013] The solvent in S2 is one or more of diethylene glycol dibutyl ether, dioctyl adipate, dibutyl phthalate and dioctyl sebacate. The mass of the solvent is 8-11% of the total mass of the dimer acid, the polyamine compound and the vinyl monomer. The vinyl monomer is one or more of methyl acrylate, hydroxypropyl acrylate, butyl acrylate, octadecyl acrylate, acrylonitrile and isooctyl acrylate.

[0014] In S2, the reaction liquid is cooled to below 80 DEG C, then a solvent is added and mixed uniformly, and then cooled to 45-60 DEG C, the vinyl monomer is added dropwise at a uniform speed within 3-4 h, and reacted while stirring, after completion, the stirring is continued for 55-65 min, and then naturally cooled to room temperature to obtain the polyamide type solid propellant slurry viscosity reducer.

[0015] A polyamide type solid propellant slurry viscosity reducer prepared by the preparation method of the polyamide type solid propellant slurry viscosity reducer according to any one of the above.

[0016] Compared with the prior art, the present application has the following beneficial technical effects:

[0017] The application discloses a preparation method of a polyamide type solid propellant slurry viscosity reducing additive, and the polyamide prepolymer is obtained by condensation reaction of dimer acid and polyamine compounds, and then the polyamide prepolymer is reacted with a vinyl monomer under the assistance of a solvent, so that the end capping and the reaction activity of the amine group can be realized. The amide bond structure in the polyamide molecule has a certain polarity, can be physically adsorbed on the surface of the filler particles, and can improve the solid-liquid interface wettability, so as to reduce the structural viscosity of the system. Meanwhile, the polyamide segment has a certain flexibility and fluidity, can form a slip layer between the polymer chains in a high temperature state, reduces the inter-chain friction, and significantly improves the flowability of the slurry. Especially, the low molecular weight polyamide or the flexible chain segment modified polyamide has good dilution and lubrication effect in the propellant slurry, and can be used as an effective viscosity reducing process additive. The end capping group (vinyl monomer) and the amide structure with polarity are introduced, can form stable bonding with the inorganic filler, have good compatibility with the organic matrix, and have chemical activity to participate in the curing reaction, can significantly reduce the viscosity of the system in the high filling slurry system, effectively improve the shear thinning behavior and flow leveling performance of the slurry, improve the casting process stability, can improve the mechanical properties of the hydroxyl terminated polybutadiene propellant and significantly reduce the slurry viscosity. Compared with the traditional low molecular plasticizer or volatile solvent type viscosity reducer, the polyamide structure is stable and not easy to volatilize, can not only meet the high temperature mixing requirement in the propellant manufacturing process, but also is non-toxic and low odor, and meets the development direction of the current clean production and green chemical industry. The preparation process does not need to use high pressure or complex equipment, and has the advantages of simple process, wide raw material source, environmental friendliness, wide raw material source, controllable cost, and the like, and is suitable for industrialized preparation and popularization and application.

[0018] The polyamide type solid propellant slurry viscosity reducing additive of the application is a polyamide prepolymer prepared by condensation polymerization of dimer acid and polyamine compounds, and the end group is regulated by using a vinyl monomer as an end capping agent, and the polyamide molecular material has uniform structure, moderate polarity and can enter the crosslinked network. The additive structure contains a polar amide group, can be effectively adsorbed on the surface of the solid particles, and can significantly improve the wettability and shear flowability of the slurry system. The vinyl monomer as the end capping agent is introduced, can help to regulate the reaction activity of the amine group, control the participation degree of the additive in the curing process, is suitable for the rheological property optimization of the solid propellant slurry system, and has a good engineering application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is an infrared spectrum of the polyamide type solid propellant simulated slurry viscosity reducing additive of Example 1 of the application.

[0020] Figure 2 It is a rheological diagram of the simulated slurry system of the polyamide type process additive described in Examples 1 to 4 of the application.

[0021] Figure 3Rheological diagram of simulated drug slurry system after adding TDI curing agent and process additive of examples 1-4 of the present application.

[0022] Figure 4 Rheological diagram of simulated drug slurry system after adding IPDI curing agent and process additive of examples 1-4 of the present application.

[0023] Figure 5 Stress-strain curve of simulated drug slurry sample of examples 1-4 of the present application.

[0024] Figure 6 SEM diagram of cross section of simulated drug slurry of example 1 of the present application (magnification 650 times).

[0025] Figure 7 SEM diagram of cross section of simulated drug slurry of example 1 of the present application (magnification 3500 times).

[0026] Figure 8 SEM diagram of cross section of simulated drug slurry of example 1 of the present application (magnification 1000 times).

[0027] Figure 9 SEM diagram of cross section of simulated drug slurry of example 1 of the present application (magnification 1500 times). DETAILED DESCRIPTION

[0028] The present application will be described in detail below with specific examples, and the description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present application.

[0029] The process additive includes 47%-67% of component I (dimer acid), 18%-44% of component II (polyamine compound), 9%-25% of component III (vinyl monomer), and solvent, and the mass of high-boiling organic solvent is 8%-11% of the total mass of component I, component II and component III.

[0030] The content of dimer (i.e. effective component) in dimer acid is greater than 98%, the polyamine compound is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, the vinyl monomer is selected from one or more of methyl acrylate, hydroxypropyl acrylate, butyl acrylate, octadecyl acrylate, acrylonitrile and isooctyl acrylate, and the solvent is high-boiling organic solvent selected from one or more of diethylene glycol dibutyl ether, dioctyl adipate, dibutyl phthalate and dioctyl sebacate.

[0031] The dimer acid and polyamine compound are added into a three-necked flask equipped with stirring device and thermometer in a set ratio, heated at 135-150°C for 4-5h to complete the condensation reaction to generate polyamide prepolymer. After the reaction, the system is cooled to below 80°C, a predetermined amount of solvent is added, and stirring is continued until the mixture is uniform. Then the system is further cooled to 45-60°C, and the vinyl monomer is slowly and evenly added to the reaction system within 3-4h while stirring to achieve the end-capping of amine group and the control of reaction activity. After the addition is completed, stirring is continued for 1h to help the homogenization of the system, the remaining reaction to proceed fully, and the cooling to speed up, and then the system is naturally cooled to room temperature to obtain a brownish red product. Finally, the reaction process is illustrated by structural formula using a single reagent (solvent is diethylene glycol dibutyl ether or dioctyl adipate or dibutyl phthalate or dioctyl sebacate) as an example.

[0032] 1 Raw materials: dimer acid, ethylenediamine, methyl acrylate;

[0033]

[0034] 2 Raw materials: dimer acid, ethylenediamine, hydroxypropyl acrylate (only the second step group outside the box is different from the raw material ratio of 1);

[0035]

[0036] 3 Raw materials: dimer acid, ethylenediamine, butyl acrylate (only the second step group outside the box is different from the raw material ratio of 1);

[0037]

[0038] 4 Raw materials: dimer acid, ethylenediamine, stearyl acrylate (only the second step group outside the box is different from the raw material ratio of 1, and the same is not shown to avoid unnecessary page occupation);

[0039]

[0040] 5 Raw materials: dimer acid, ethylenediamine, acrylonitrile (only the second step group outside the box is different from the raw material ratio of 1);

[0041]

[0042] 6 Raw materials: dimer acid, ethylenediamine, isooctyl acrylate (only the second step group outside the box is different from the raw material ratio of 1, and the same is not shown to avoid unnecessary page occupation);

[0043]

[0044] 7 Raw materials: dimer acid, diethylenetriamine, methyl acrylate;

[0045]

[0046] 8 Raw materials: dimer acid, diethylene triamine, hydroxypropyl acrylate (same as 7 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0047]

[0048] 9 Raw materials: dimer acid, diethylene triamine, butyl acrylate (same as 7 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0049]

[0050] 10 Raw materials: dimer acid, diethylene triamine, stearyl acrylate (same as 7 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0051]

[0052] 11 Raw materials: dimer acid, diethylene triamine, isooctyl acrylate (same as 7 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0053]

[0054] 12 Raw materials: dimer acid, triethylene tetramine, methyl acrylate

[0055]

[0056] 13 Raw materials: dimer acid, triethylene tetramine, hydroxypropyl acrylate (same as 12 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0057]

[0058] 14 Raw materials: dimer acid, triethylene tetramine, butyl acrylate (same as 12 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0059]

[0060] 15 Raw materials: dimer acid, triethylene tetramine, hydroxy stearyl acrylate (same as 12 raw materials except for the second step out-group group, to avoid unnecessary page occupation, do not display the same place)

[0061]

[0062] 16 Raw materials: dimer acid, triethylene tetramine, isooctyl acrylate (only the second step out-of-frame group is different from that of 12 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0063]

[0064] 17 Raw materials: dimer acid, tetraethylene pentamine, methyl acrylate

[0065]

[0066] 18 Raw materials: dimer acid, tetraethylene pentamine, hydroxypropyl acrylate (only the second step out-of-frame group is different from that of 17 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0067]

[0068] 19 Raw materials: dimer acid, tetraethylene pentamine, butyl acrylate (only the second step out-of-frame group is different from that of 17 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0069]

[0070] 20 Raw materials: dimer acid, tetraethylene pentamine, stearyl acrylate (only the second step out-of-frame group is different from that of 17 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0071]

[0072] 21 Raw materials: dimer acid, tetraethylene pentamine, acrylonitrile (only the second step out-of-frame group is different from that of 17 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0073]

[0074] 22 Raw materials: dimer acid, tetraethylene pentamine, isooctyl acrylate (only the second step out-of-frame group is different from that of 17 raw materials, to avoid unnecessary page occupation, the same places are not displayed)

[0075]

[0076] Example 1

[0077] Into a three-necked flask equipped with a stirring device and a thermometer, 56 g of dimer acid and 20.6 g of diethylenetriamine were added, and the reaction was heated at 145°C for 4 h to complete the condensation reaction to form a polyamide prepolymer. After the reaction was completed, the system was cooled to 75°C, 9.5 g of diethylene glycol dibutyl ether was added, and the stirring was continued until the mixture was uniform. Then the system was further cooled to 60°C, and 15.9 g of acrylonitrile was slowly and evenly added into the reaction system within 3.5 h. After the addition was completed, the stirring was continued for 1 h, and the system was naturally cooled to room temperature. Finally, a brownish red product was obtained, which was the multifunctional polyamide type solid propellant slurry viscosity reducing additive.

[0078] Example 2

[0079] Into a three-necked flask equipped with a stirring device and a thermometer, 56 g of dimer acid and 20.6 g of diethylenetriamine were added, and the reaction was heated at 145°C for 4 h to complete the condensation reaction to form a polyamide prepolymer. After the reaction was completed, the system was cooled to 75°C, 9.5 g of diethylene glycol dibutyl ether was added, and the stirring was continued until the mixture was uniform. Then the system was further cooled to 60°C, and 15.9 g of acrylonitrile was slowly and evenly added into the reaction system within 3.5 h. After the addition was completed, the stirring was continued for 1 h, and the system was naturally cooled to room temperature. Finally, a brownish red product was obtained, which was the multifunctional polyamide type solid propellant slurry viscosity reducing additive. The reaction processes of the above two examples are as follows (the first and second examples are different only in the second step, and the same parts are not shown to avoid unnecessary page occupation):

[0080]

[0081]

[0082] Example 3

[0083] Into a three-necked flask equipped with a stirring device and a thermometer, 56 g of dimer acid and 20.6 g of diethylenetriamine were added, and the reaction was heated at 145°C for 4 h to complete the condensation reaction to form a polyamide prepolymer. After the reaction was completed, the system was cooled to 75°C, 9.5 g of diethylene glycol dibutyl ether was added, and the stirring was continued until the mixture was uniform. Then the system was further cooled to 60°C, and 15.9 g of acrylonitrile was slowly and evenly added into the reaction system within 3.5 h. After the addition was completed, the stirring was continued for 1 h, and the system was naturally cooled to room temperature. Finally, a brownish red product was obtained, which was the multifunctional polyamide type solid propellant slurry viscosity reducing additive.

[0084] Example 4

[0085] Into a three-necked flask equipped with a stirring device and a thermometer, 56 g of dimer acid and 29.2 g of triethylene tetramine were added, and the reaction was heated at 145°C for 4 h to complete the condensation reaction to generate a polyamide prepolymer. After the reaction was completed, the system was cooled to 70°C, 9.5 g of dioctyl sebacate was added, and stirring was continued until the mixture was uniform. Then the system was further cooled to 60°C, and 15.9 g of acrylonitrile was slowly and evenly added into the reaction system within 3.5 h. After the addition was completed, stirring was continued for 1 h, and the system was naturally cooled to room temperature, and finally a brown-red product was obtained, which was the multifunctional polyamide type solid propellant slurry viscosity reducing additive.

[0086] Figure 1 is an infrared spectrum of the multifunctional polyamide type solid propellant slurry viscosity reducing additive, and the peak at 3303 cm -1 is a —NH— stretching vibration peak of the primary amine in the polyamide; the peaks at 2854 cm -1 and 2922 cm -1 correspond to the anti-symmetrical stretching vibration and symmetrical stretching vibration of —CH2— in the polyamide molecule, respectively; the peak at 2245 cm -1 is a stretching vibration peak of —CN in acrylonitrile; the peaks at 1645 cm -1 and 1542 cm -1 are —CO stretching vibration and —NH— bending vibration of the amide bond; the peak at 1456 cm -1 corresponds to the bending vibration of —CH2—. Thus, it can be seen that the polyamide type solid propellant slurry viscosity reducing additive is prepared.

[0087] Figure 2 is the rheological property of the multifunctional polyamide type solid propellant slurry viscosity reducing additive (abbreviated as polyamide type process additive) of examples 1-4 of the present application applied to the slurry system. In the experiment, the simulated slurry provided by Xi'an Beihua Huan Chemical Industry Co., Ltd. (not containing an energetic component, which can effectively simulate the rheological behavior of the HTPB based solid propellant slurry in terms of viscosity and shear response) was used as a substitute material to simulate the HTPB based solid propellant system, and the rheological behavior thereof was characterized and analyzed. First, the polyamide type process additive was added into the simulated slurry at a mass ratio of 2‰, and was uniformly dispersed, and a DHR-1 type rotary rheometer of TA Company, USA was used to perform rheological testing on the simulated slurry, the testing temperature was 60°C, the clamp was a 40 mm parallel plate, and the shear rate was 0.01-10 s -1 The results show that all the slurry presents a typical non-Newtonian fluid characteristic, and presents a shear thinning behavior that the viscosity is significantly reduced with the increase of the shear rate. After the process additive of different formulations (numbered as 1#, 2#, 3# and 4#) is added, the overall viscosity of the slurry system is significantly reduced compared with that without the addition, which indicates that the synthesized polyamide type additive has obvious effects in improving the flowability of the slurry and reducing the structural viscosity of the system.

[0088] Figure 3 is the rheological diagram of the simulated propellant slurry with the addition of curing agent TDI and polyamide type process additive, Figure 4 is the rheological diagram of the simulated propellant slurry with the addition of curing agent IPDI and polyamide type process additive. Through Figure 2 the rheological performance analysis, further adding curing agent toluene diisocyanate TDI and isophorone diisocyanate IPDI in the simulated propellant slurry is used to simulate the rheological behavior change under the curing state of the propellant. The experimental results show that after adding the curing agent, the viscosity of the propellant slurry becomes smaller, which is mainly because the toluene diisocyanate and isophorone diisocyanate curing agent can chemically react with the hydroxyl groups in the propellant components to form a cross-linked structure. In the early stage of the reaction, it will cause the molecular chains in the system to rearrange or depolymerize, thereby reducing the overall viscosity. In addition, during the addition of the curing agent, the reaction will release heat, causing the temperature of the system to rise, thereby causing the viscosity of the propellant slurry to decrease. The data of adding 1#, 2#, 3#, and 4# process additives show that no matter whether isophorone diisocyanate (IPDI) or toluene diisocyanate (TDI) is used as the curing system, the multifunctional polyamide type process additive all shows excellent viscosity reduction effect.

[0089] Figure 5 is Figure 3 the tensile diagram of the simulated propellant slurry sample after curing in Example 1, and Table 1 is the mechanical property curve parameters of the simulated sample after curing. The same is cut into dumbbell-shaped and measured for tensile strength, Figure 3 The influence of the four process additives on the mechanical strength of different adhesive films in Example 1 is shown in Figure 5 The data results show that after adding different multifunctional polyamide type process additives, the simulated propellant slurry sample shows good mechanical properties, especially the sample 4 added with the 4# process additive, whose tensile strength is 23.79 MPa, and the elongation at break is more than 100%. The increase in the tensile strength of the simulated propellant slurry system indicates that it has obvious effect in enhancing the strength of the matrix. The decrease in the elongation at break is due to the introduction of the additive, which increases the cross-linking density and internal interaction of the system, limits the movement ability of the high molecular chain segment, and weakens the plastic deformation ability of the material, but does not affect the normal use.

[0090] Table 1 Mechanical property curve parameters of the simulated propellant slurry sample

[0091]

[0092] Figure 6 and Figure 7 is Figure 3 the scanning electron microscope (SEM) image of the cross section of the simulated propellant slurry sample (without adding process additive) after curing in Example 1, Figure 8 and Figure 9The cross-section morphology of the sample without adding the process additive is shown in Fig. 2. It can be seen that the filler particles are unevenly distributed in the cross-section of the sample, and there is a certain degree of flocculation and agglomeration phenomenon, and the interface between the particles is poor. After adding the process additive 4#, the filler is more evenly dispersed in the binder matrix, the interface is more closely combined, and there is no obvious agglomeration structure, and the overall cross-section is more compact and smooth. This shows that the process additive can significantly improve the interface wettability between the filler and the binder, enhance the dispersion stability of the filler, thereby effectively reducing the structural viscosity of the slurry system caused by particle agglomeration, and then realizing the reduction of the overall viscosity and the improvement of the flow performance of the slurry.

Claims

1. A method for preparing a polyamide solid propellant slurry viscosity reducing agent, characterized in that: The following steps are involved: S1, condensing a dimer acid with a polyamine compound at 135-150° C. to generate a polyamide prepolymer in the obtained reaction solution; S2, cooling the reaction solution, adding a solvent and mixing evenly, then adding a vinyl monomer at 45-60°C for reaction, and finally cooling to room temperature to obtain a polyamide solid propellant slurry viscosity reducing agent; The dimer acid, polyamine compound and vinyl monomer are used in amounts of 47% to 67%, 18% to 44% and 9% to 25% by mass respectively.

2. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, wherein: In the dimer acid described in S1, the content of dimer is greater than 98%.

3. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, wherein: The polyamine compound described in S1 is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

4. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, wherein: The dimer acid described in S1 is condensed with the polyamine compound at 135-150° C. for 4-5 hours to generate a polyamide prepolymer in the obtained reaction solution.

5. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, wherein: The solvent described in S2 is one or more of diethylene glycol dibutyl ether, dioctyl adipate, dibutyl phthalate and dioctyl sebacate.

6. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 5, characterized in that: The mass of the solvent is 8%-11% of the total mass of the dimer acid, the polyamine compound and the vinyl monomer.

7. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, characterized in that: The vinyl monomer described in S2 is one or more of methyl acrylate, hydroxypropyl acrylate, butyl acrylate, octadecyl acrylate, acrylonitrile and isooctyl acrylate.

8. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 1, characterized in that: In S2, the reaction liquid is cooled to below 80°C, and then a solvent is added and mixed evenly. After that, the reaction liquid is cooled to 45-60°C. Within 3-4 hours, the vinyl monomer is added dropwise at a uniform speed while stirring and reacting. Finally, the temperature is cooled to room temperature to obtain a polyamide solid propellant slurry viscosity reducing agent.

9. The method for preparing the polyamide solid propellant slurry viscosity reducing agent according to claim 8, characterized in that: After the reaction in S2 is completed, stirring is continued for 55 to 65 minutes, and then naturally cooled to room temperature to obtain a polyamide solid propellant slurry viscosity reducing additive.

10. A polyamide solid propellant slurry viscosity reducing agent obtained by the preparation method of the polyamide solid propellant slurry viscosity reducing agent according to any one of claims 1 to 9.

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