Polyurea rapid curing solid propellant 3d printing paste

Abstract

The present application relates to a kind of polyurea quick curing solid propellant 3D printing paste, is made of A, B component, wherein, A is: first binder 15%, oxidant 70%, metal burning agent 15%;B is: second binder 13%-15%, oxidant 69%, metal burning agent 15%-16%, functional adjuvant 0%-2%.After the paste of prepared A and B component is accurately metered, extruded into static mixing pipe, after realizing the accurate, fast, uniform mixing of two materials, according to the designed path, the printing of solid propellant 3D printing paste is completed, and is quickly cured into shape at room temperature.The present application breaks through the limitation of traditional propellant needing subsequent finishing, production cycle is longer, qualified rate is low, process is complicated, production energy consumption is big and numerous safety problems, realizes the preparation of accurate, fast curing solid propellant at room temperature, provides new way and new scheme for solid propellant technology.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid propellants, and specifically provides a polyurea-based room-temperature rapid-curing composite solid propellant 3D printing slurry and a propellant. BACKGROUND

[0002] 3D printing technology has been widely researched and discussed in various manufacturing industries, but given the strict requirements of energetic materials on safety and environment, 3D printing technology is less researched and applied in the field of energetic materials, mainly focusing on the direction of initiating explosive. According to the existing literature reports, the 3D printing technology is mainly the technical approach and type in Table 1.

[0003] Table 1 Classification of technical approaches of 3D printing technology

[0004]

[0005] According to the characteristics of solid propellants and the characteristics of the technical approaches in Table 1, it can be seen that FDM, DMLS, EBM and SLM technologies are only suitable for metal materials, so the above technologies are not suitable for 3D printing of solid propellants. The melting points of the materials applied by FDM, SHS and SLS technologies are relatively high, and for the solid propellant system, high temperature will lead to reduced safety, so the above technologies applied to 3D printing of solid propellants will face safety problems.

[0006] As analyzed above, the melting points of the materials applied by FDM, SHS and SLS technologies are relatively high, and for the solid propellant system, high temperature will lead to reduced safety, so the above technologies applied to 3D printing of solid propellants will face safety problems. From the principle, the light curing molding process and the fusion deposition molding process can be used for 3D printing of solid propellants, but the light-sensitive acrylic resin obtained after light curing has a low elongation, which cannot meet the basic requirements of the elongation of the propellant binder, and the light-sensitive acrylic resin needs to be modified to improve its elongation; the melting temperature of the thermoplastic plastic used in the fusion process is relatively high (greater than 180℃), which is difficult to meet the safety requirements; the thermoplastic elastomer has excellent mechanical properties and can meet the requirements of strength and elongation of the propellant, but the melting temperature of the existing thermoplastic elastomer is also relatively high. On the other hand, due to the penetration of ultraviolet light blocked by aluminum powder in the propellant formula, it is difficult to achieve complete and rapid curing of the printing droplets, especially when the content of aluminum powder in the propellant is greater than 10%, the propellant slurry at the bottom of the droplet is difficult to cure. SUMMARY

[0007] The purpose of the present application is to provide a polyurea rapid-curing solid propellant 3D printing slurry and a preparation method.

[0008] The technical solution of the present application is: a kind of polyurea quick curing solid propellant 3D printing paste, which is composed of A component and B component, wherein,

[0009] The A component is composed of 15% of the first adhesive, 70% of the oxidant and 15% of the metal combustion agent by mass percentage.

[0010] The B component is composed of 13%-15% of the second adhesive, 69% of the oxidant, 15%-16% of the metal combustion agent and 0%-2% of the functional additive by mass percentage; the molar ratio of the cyanate in the first adhesive to the sum of the hydroxyl and amino in the second adhesive is 1.01-1.05.

[0011] Preferably, the first adhesive is isocyanate, which can be one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate, p-phenylene diisocyanate, p-phenylene dimethylene diisocyanate and tetramethyl dimethylene diisocyanate.

[0012] Preferably, the first adhesive is a prepolymer of polyether (ester) polyol and isocyanate, wherein the polyether polyol is one of polycaprolactone polyol, polycarbonate polyol, polypropylene oxide polyol, polyethylene glycol ether, polypropylene glycol ether, polyglycerol ether, polytetrahydrofuran ether diol and polytetramethyl ether diol.

[0013] Preferably, the first adhesive is a prepolymer of amino polyether and isocyanate, wherein the terminal amino polyether can be one of polyether diamine, polyether triamine, polypropylene oxide diamine, polypropylene oxide triamine and polytetrahydrofuran diamine.

[0014] Preferably, the second adhesive is any one of terminal hydroxyl resin or terminal amino resin, wherein the terminal hydroxyl resin can be one of terminal hydroxyl polybutadiene resin, terminal hydroxyl hydrogenated polybutadiene resin, terminal hydroxyl epoxidized polybutadiene resin and terminal hydroxyl polybutadiene-acrylonitrile resin; the terminal amino resin can be one of methyl etherified amino resin, ethyl etherified amino resin, butyl etherified amino resin and methyl butyl mixed etherified amino resin.

[0015] Preferably, the second adhesive is a prepolymer of terminal hydroxyl resin and terminal amino chain extender, wherein the terminal amino chain extender can be one of diethyl toluene diamine, triethyl benzene diamine, isophorone diamine, m-phenylene diamine, hexanediamine and ethylenediamine.

[0016] Preferably, the oxidant can be one of ammonium perchlorate, ammonium nitrate, octogen and hexogen.

[0017] Preferably, the metal combustion agent can be one of lithium, beryllium, boron, magnesium, aluminum or magnesium-aluminum alloy.

[0018] Preferably, the functional assistant can be one of acetylacetone iron, triphenyl bismuth, dibutyl tin dilaurate, di-n-octyl tin dimethicone, isophorone diisocyanate and tri-nitrophenyl bismuth.

[0019] The application also provides a preparation method of the polyurea fast-curing solid propellant, which is realized by the following steps:

[0020] (1) raw material pretreatment: after the first binder and the second binder are vacuumed to remove water at a certain temperature, they are ready for use;

[0021] (2) preparation of slurry: the first binder and the second binder in step (1) are respectively added to oxides, metal combustion agents and functional assistants, and kneaded under vacuum to obtain 3D printing propellant slurry components A and B;

[0022] (3) design and modeling of solid propellant shape: three-dimensional modeling is performed on the solid propellant shape to be prepared by using three-dimensional drawing software, data conversion is performed on the obtained three-dimensional model, and the microcomputer system is inputted, and the path planning of 3D printing is completed;

[0023] (4) 3D printing of solid propellant: the components A and B of propellant slurry obtained in step (2) are respectively extruded into precision metering pumps, rapidly mixed through a static mixing tube, and then printed layer by layer through a nozzle with different inner diameters by 3D printing technology, and fast curing is completed at room temperature.

[0024] Preferably, the vacuum kneading time of components A and B is 30 min.

[0025] Preferably, the rapid mixing time in the static mixing tube is 10s-30s.

[0026] Preferably, the room temperature fast curing time is 1min-15min, preferably 4min-5min.

[0027] Compared with the prior art, the application has the characteristics of precision, rapidity, controllability and safe processing, breaks through the limitations of traditional propellant preparation technology, such as the need for subsequent finishing, long production cycle, low qualified rate, complicated process and numerous safety problems, realizes the preparation of 3D printing slurry of high solid content solid propellant and room temperature fast curing, and provides an elastomeric polymer with good mechanical properties and fast curing through the study on the structure and performance relationship of the binder, curing agent and catalyst, which effectively shortens the shape maintaining time of the binder system and provides a curing system for printing propellant. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Figure 1 is a 3D printing equipment diagram for polyurea fast-curing solid propellant slurry;

[0029] wherein, Figure 1 In the figure, 1 is a first drug slurry; 2 is a second drug slurry; 3 is a first switch; 4 is a second switch; 5 is a first metering pump; 6 is a second metering pump; 7 is a first check valve; 8 is a second check valve; 9 is a first overflow valve; 10 is a second overflow valve; 11 is a static mixer; 12 is a third switch; and 13 is a discharge port.

[0030] Figure 2 A 3D printing device for polyurea rapid curing solid propellant slurry is provided. DETAILED DESCRIPTION

[0031] The technical solutions of the present application will be described clearly and completely below in combination with the preferred embodiments of the present application. The described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] In combination with Figure 1 The present application provides a 3D printing device for polyurea rapid curing solid propellant slurry, which comprises a first switch 3, a second switch 4, a first metering pump 5, a second metering pump 6, a first check valve 7, a second check valve 8, a first overflow valve 9, a second overflow valve 10, a static mixer 11, a third switch 12, and a discharge port 13.

[0033] The present application aims at the problems of the traditional solid propellant grain forming process, such as complex process, lack of universal rapid forming conditions, relatively fixed process route and production equipment after operation, lack of flexibility, difficulty in reconfiguration, high investment cost, uneven mixing of solid fillers, long production cycle, need for manual finishing of finished products, and inability to directly manufacture complex shape solid propellant, and develops a polyurea two-component rapid curing propellant 3D printing slurry and a preparation method thereof.

[0034] The polyurea is an elastomer generated by the reaction of the first binder in component A with the second binder in component B. The reaction speed and mechanical properties of the polyurea have the characteristics that the reaction activity can be adjusted with the changes of the structure and ratio of the first binder and the second binder. Therefore, by adjusting the structure and ratio of the first binder and the second binder, a curing system conforming to the rapid curing extrusion printing process can be obtained. The premixed slurry A (first drug slurry) and slurry B (second drug slurry) are respectively metered into the static mixing pipe, and are extruded and printed to the working surface while being mixed. By reasonably matching the extrusion speed and gel speed of the drug slurry, the first binder and the second binder are used as the polymer network, and the oxidizing agent, metal combustion agent, and functional additive are used as the energetic filler, the process of metering, mixing, and printing of the system with a solid content of 85% is realized, and the curing temperature is ≤35℃.

[0035] The first adhesive is composed of any one of the three types of prepolymers, i.e., isocyanate, polyether (ester) polyol and isocyanate, and amino polyether and isocyanate.

[0036] The reaction mechanism can be generally represented as:

[0037]

[0038] In order to reduce the viscosity of the prepolymer at room temperature, so as to make the viscosity and volume of the prepolymer component and the chain extender in the second step reaction more close, and to improve the accuracy of the dosage and the mixing effect, the amount of isocyanate can be controlled to be more than the amount of polyol or amine, and the unreacted diisocyanate exists in the prepolymer in a free state. The prepared prepolymer can be a mixture of prepolymer and diisocyanate.

[0039] The reaction speed of isocyanate and amino-terminated polymer is extremely fast, which can be gelled in 5s and cured in 1min, which is the basic feature of spray polyurea. In the spraying process, the viscosity of the slurry is low, and the addition amount of solid fillers is limited.

[0040] The curing speed needs to be matched and coordinated with the dosing, mixing and extrusion speed of the two-component slurry, and the gelation speed. If the curing speed is too fast, the gelation will occur in the mixing and extrusion process. If the curing speed is too slow, the slurry will flow on the working surface and the thickness will be uneven. The curing speed of the two-component slurry is closely related to the molecular weight of the prepolymer, the content of isocyanate, the type of chain extender of B component, the content of chain extender, the structure of amino polyether and catalyst, etc.

[0041] From the selection of chain extenders with different types and amounts, the viscosity of amino compounds and the overall reaction and curing speed of the system, etc. Process parameters mainly include aromatic diamine chain extender and aliphatic diamine chain extender. The aromatic diamine chain extender is relatively mild in activity, and the polyurea resin with better mechanical and chemical properties can be obtained. The aliphatic diamine chain extender is relatively active in the reaction process, which not only can rapidly react with various isocyanates containing isocyanate groups, but also can rapidly react and cure. Accordingly, the slurry gelation and curing speed can be flexibly adjusted according to the process and performance needs.

[0042] The selected diaminobis chain extender is: diethyl toluene diamine, commonly known as E100, its main composition is a mixture of isomers of diethyl toluene diamine, 3,5-diethyl-2,4-diaminotoluene and 3,5-diethyl-2,6-diaminotoluene, and low content of hydroxy m-phenylenediamine and triethylphenylenediamine, etc., abbreviated as DETDA. Isophorone diamine, abbreviated as IPDA, belongs to the type of aliphatic diaminobis chain extender, which can be used in all reactions containing amine chain extender. As a chain extender in polyurea resin reaction, its reaction rate is much faster than E100, and the mechanical properties are excellent. The order of different diaminobis chain extender composition on solution viscosity and reaction polymerization speed is: m-phenylenediamine > hexamethylene diamine > ethylenediamine > moca.

[0043] The type of chain extender in polyurea system not only affects the reaction curing time of the system, but also has different degrees of influence on the mechanical tensile strength and impact strength of the obtained polyurea resin. Therefore, when selecting the polyurea resin chain extender, the overall performance of the product required should be considered, and the physical and chemical conditions required should be considered. According to the performance requirements, the amine chain extender is selected, the component ratio is allocated, and the overall performance index of polyurea is improved. The physicochemical properties of the selected chain extender are shown in Table 2.

[0044] Table 2 Performance of different types of chain extenders

[0045]

[0046]

[0047] The raw materials used are:

[0048] The substances listed in Table 3 are representatives of the various technical solutions described in the present application, and are not limited to the substances in Table 3 in actual implementation.

[0049] Table 3 Raw materials

[0050]

[0051]

[0052] Example 1:

[0053] The formulation of Example 1 is shown in Table 4, and the raw materials of A component and B component are weighed according to Table 3 and Table 4, and the specific process is as follows:

[0054] (1) Raw material pretreatment: 1-1 with relative molecular mass of 1000 purchased was vacuum dehydrated at 100-110°C for 2h, cooled, and then 4-1 was added and reacted at 80°C for 2h. When the NCO mass fraction reached 10% of the designed NCO%, the first adhesive was obtained. 5-1 was vacuumed at 100-120°C for 1.5-2h, and then 6-1 was added to obtain the second adhesive.

[0055] (2) Preparation of slurry: according to Table 4, the A component raw material and the B component raw material were kneaded under vacuum for 30min respectively to obtain the 3D printing solid propellant slurry.

[0056] (3) Design and modeling of solid propellant shape: three-dimensional modeling software was used to model the solid propellant shape to be prepared, and the obtained three-dimensional model was data-converted and input into the microcomputer system to complete the path planning of 3D printing.

[0057] (4) 3D printing of solid propellant slurry: the A component and the B component propellant slurry obtained in step (2) were respectively extruded into the metering pump, rapidly and uniformly mixed through the static mixing tube, and then printed layer by layer through different inner diameter needles by 3D printing technology, wherein the mixing ratio of the A component and the B component was 1.03 according to the sum of the isocyanate molar number of the A component and the hydroxyl and amino molar number of the B component.

[0058] (5) Rapid solidification of solid propellant: the rapid solidification was completed within 4-5min at room temperature, and the actual picture is shown in Figure 2 .

[0059] Table 4 Formulation of examples (% by mass)

[0060]

[0061]

[0062] Table 5 Mechanical properties of propellants with different formulations

[0063] Formulation Tensile strength / MPa Room temperature elongation / % Example 1 0.75 50 Example 2 0.65 73 Example 3 0.76 51 Example 4 0.8 57

[0064] The first adhesive, the second adhesive, the A component and the B component formulations in examples 2-4 were prepared according to Table 3 and Table 4, and the processing process was the same as that in example 1. The mixing ratio between the A component and the B component in examples 2-4 was according to the sum of the isocyanate molar number of the A component and the hydroxyl and amino molar number of the B component. The rapid solidification 3D printing solid propellants prepared in examples 1-4 were tested for tensile strength and room temperature elongation performance, and the execution standard was GB / T19250-2013. The performance data results are shown in Table 5.

[0065] Through the test of the performance of the polyurea fast-curing solid propellant 3D printing paste prepared by the preferred embodiments 1-4, it can be known by comparison that the embodiment 2 is completed in 5 min at room temperature, the tensile strength is 0.65 MPa, and the normal temperature elongation can reach 73%. Compared with the traditional solid propellant curing, which needs to be cured for about one week under heating conditions, the preparation of the solid propellant by using the fast-curing solid propellant 3D printing paste can save a lot of manpower and material resources, can avoid a large amount of energy loss, and can reduce economic loss.

Claims

1. A polyurea rapid-curing solid propellant 3D printing paste, characterized in that, Consists of A component and B component, wherein, The A component is composed of 15% of first adhesive, 70% of oxidizer and 15% of metal combustion agent by mass percentage; The B component is composed of 13%-15% of second adhesive, 69% of oxidizer, 15%-16% of metal combustion agent and 0%-2% of functional additive by mass percentage; The ratio of the number of cyanate moles in the first adhesive to the total number of hydroxyl and amino groups in the second adhesive is 1.01-1.05; The first adhesive is any one of isocyanate, prepolymer of polyether polyol and isocyanate, or prepolymer of amino polyether and isocyanate; The second adhesive is any one of terminal hydroxyl resin, terminal amino resin, or prepolymer of terminal hydroxyl resin and terminal amino chain extender; The isocyanate is one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate, p-phenylene diisocyanate, p-phenylene dimethylene diisocyanate, tetramethyl dimethylene diisocyanate; The polyether polyol is one of polycaprolactone polyol, polycarbonate polyol, polypropylene oxide polyol, polyethylene glycol ether, polypropylene glycol ether, polyglycerol ether, polytetrahydrofuran ether diol; The amino polyether is one of polyether diamine, polyether triamine, polypropylene oxide diamine, polypropylene oxide triamine, polytetrahydrofuran diamine; The terminal hydroxyl resin is one of terminal hydroxyl polybutadiene resin, terminal hydroxyl hydrogenated polybutadiene resin, terminal hydroxyl epoxidized polybutadiene resin, terminal hydroxyl polybutadiene-acrylonitrile resin; The terminal amino resin is one of methyl etherified amino resin, ethyl etherified amino resin, butyl etherified amino resin, methyl butyl mixed etherified amino resin; The terminal amino chain extender is one of diethyl toluene diamine, triethyl benzene diamine, isophorone diamine, m-phenylene diamine, hexanediamine, ethylenediamine.

2. The 3D printing paste of claim 1, wherein, The oxidizer is one of ammonium perchlorate, ammonium nitrate, octogen, hexogen; The metal combustion agent is one of lithium, beryllium, boron, magnesium, aluminum or magnesium-aluminum alloy; The functional additive is one of acetylacetone iron, triphenyl bismuth, dibutyl tin dilaurate, di-n-octyl tin disilicate, isophorone diisocyanate and triphenyl bismuth.

3. The method for preparing solid propellant based on the 3D printing slurry according to any one of claims 1-2, comprising the following steps: (1) The first adhesive and the second adhesive are vacuumed to remove water at a certain temperature and then standby; (2) The first adhesive and the second adhesive in step (1) are respectively added into the oxidant, metal combustion agent and functional additive, and kneaded under vacuum to obtain the A component and the B component of the 3D printing propellant slurry; (3) The shape of the solid propellant to be prepared is modeled by three-dimensional drawing software, the three-dimensional model is data-converted, and the data-converted model is input into the microcomputer system to complete the path planning of 3D printing; (4) The A component and the B component obtained in step (2) are respectively extruded into the metering pump, rapidly mixed through the mixing pipe, and then printed layer by layer through the nozzle with different inner diameters by 3D printing technology, and rapidly solidified at room temperature.

4. The method of claim 3, wherein, In step (2), the A component and the B component are kneaded under vacuum for 30 min.

5. The method of claim 3, wherein, In step (4), the A component and the B component are respectively extruded into a precision metering pump, rapidly mixed through a static mixing tube for 10 s~30 s, and rapidly cured at room temperature for 4 min-5 min.

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