A solid rocket motor thermal-optically cured insulation-liner material and method of making same

Abstract

The application discloses a kind of solid engine heat-light curing heat-insulating-lining materials and preparation method thereof, the heat / light curing heat-insulating-lining material is with teleclaw type epoxy acrylate phosphate ester resin as matrix material, adds fiber, ablation-resistant resin and plasticizer and other auxiliary agents preparation, using scraping coating forming process, slurry is shaped in the inner wall of solid engine shell, carries out preliminary solidification by ultraviolet irradiation, after solid propellant charge is completed, the material is synchronous thermosetting with propellant molding.Can solve the problems such as long semi-solidification period of traditional hydroxyl lining, curing degree is not measurable and bonding strength margin is not high;Heat / light curing heat-insulating-lining material as engine heat protection material, it has the advantages such as ablation resistance and propellant bonding strength, etc., can solve the problems such as interface debonding caused by the great difference between existing rubber-based heat-insulating layer and hydroxyl lining resin system, realize the efficient, high-quality and batch production of engine heat-insulating, lining.

Description

Technical Field

[0001] This invention belongs to the field of solid rocket motor insulation materials and propellant loading technology, specifically relating to a solid rocket motor thermal-photocurable insulation-lining material and its preparation method. Background Technology

[0002] Solid rocket motors are the power units for missiles, rockets, and other weapons systems. They offer advantages such as high mobility, low cost, ease of maintenance, and simple manufacturing processes, and are widely used in military, aerospace, and national economic development. Currently, the thermal insulation layer of solid rocket motors primarily uses nitrile butadiene rubber (NBR) and EPDM rubber-based insulation materials. These thermal protection layers are fabricated manually or using vacuum bonding processes. The liner is mainly made of hydroxyl-terminated polybutadiene (PTB) as the base resin, with added reinforcing agents, plasticizers, curing agents, and other additives. It is fabricated using solvent dilution or blade coating processes, and undergoes pre-curing at 50℃-70℃ for 3-6 hours to achieve "semi-curing" before propellant loading. Due to the differences in the resin systems of the rubber-based insulation layer, the NBR liner, and the propellant base resin, the mechanical, compatibility, and chemical properties of the materials on both sides of the insulation / liner / propellant interface differ significantly. This leads to bulging, gap-like, tight-fitting, and spot-like adhesion defects, making the insulation / liner / propellant interface a weak point. Under complex external loads, this interface is prone to debonding and other quality problems.

[0003] There are already relevant studies, such as Chinese patent application number CN202111508707.X, which discloses the independent synthesis and preparation of telechelic epoxy phosphate resin. Based on the thermal / photocurable ablation-resistant resin properties, a formulation suitable for integrated insulation / lining material of solid rocket motors is designed and developed. It utilizes the thermal / photocurable properties of telechelic epoxy phosphate resin to solve the problems of long semi-curing cycle and unmeasurable curing degree of lining material, while also possessing ablation resistance and mechanical properties, meeting the performance requirements of engine insulation layer, and solving quality problems such as interface adhesion between insulation / lining / propellant.

[0004] For example, Chinese patent application CN202210871357.1 discloses a formulation and preparation method for a thermal insulation / lining material based on spray molding technology. Chinese patent application CN201610672693.8 reports a method for preparing a room-temperature photocurable polyurethane acrylate ionomer emulsion thermal insulation material. Deng Jianru et al. reported a study on the synthesis and application of a photocurable resin for solid rocket motor linings; this photocurable lining material exhibits good adhesion strength to the thermal insulation layer and can effectively hinder the migration of small molecule plasticizers.

[0005] However, the traditional hydroxyl-butyl liner has problems such as long semi-curing cycle and unpredictable curing degree. It is necessary to explore a new technology route for the production of solid fuel engine insulation / liner materials. Summary of the Invention

[0006] To address the problems of long semi-curing cycles and unpredictable curing degrees in traditional hydroxyl-butadiene (HbA1c) liners, this invention provides a thermo- and photo-curable insulation-liner material for solid rocket motors and its preparation method. This invention pioneers a new technical approach different from the methods and techniques used in existing publicly available literature on insulation / liner materials, photo-curable insulation materials, and photo-curable liners. It represents a novel approach for manufacturing solid rocket motor insulation / liner materials, achieving integrated molding of the insulation / liner through material formulation design and molding processes, thereby improving the interfacial strength of the insulation layer / liner / propellant bonding in solid rocket motors. On one hand, it solves the problems of long semi-curing cycles, unpredictable curing degrees, and low bonding strength margins associated with traditional HbA1c liners. On the other hand, the thermo- and photo-curable insulation / liner material, as a thermal protection material for engines, possesses advantages such as ablation resistance and high propellant bonding strength. It can resolve issues such as interfacial debonding caused by significant differences in the resin systems of existing rubber-based insulation layers and HbA1c liners, enabling high-efficiency, high-quality, and mass production of engine insulation and liners, providing a new solution for the manufacture of solid rocket motor insulation coating materials.

[0007] Technical principle of the invention:

[0008] The present invention discloses a solid propellant engine thermo-photocurable insulation-lining material. This thermo-photocurable insulation-lining material is prepared with telechelic epoxy acrylate phosphate resin as the matrix material and additives such as fibers, ablation-resistant resin and plasticizers. It adopts a scraping molding process to form the slurry on the inner wall of the solid propellant engine casing, and performs preliminary curing by ultraviolet light irradiation. After the solid propellant is loaded, the material and the propellant are simultaneously thermo-cured.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A solid-state engine thermo-photocurable insulation-lining material is made of the following components in the indicated weight percentages: 40%-60% telechelic epoxy acrylate phosphate resin, 10%-20% fiber filler, 5%-10% binder, 5%-15% ablation resistant resin, 8%-12% reinforcing agent, 2%-5% reactive diluent monomer, 2%-3% photoinitiator, and 3%-5% plasticizer;

[0011] The molecular weight of the telechelic epoxy phosphate resin is one or more of 3000, 5000 and 7000;

[0012] The fiber filler is selected from one or two of basalt fiber, high silica fiber and alumina fiber, and the mixing ratio of the two fibers is 1:1 to 1:5.

[0013] The adhesive is selected from one or two of type III hydroxyl-terminated polybutadiene and epoxy resin, and the proportion of multiple adhesives can be arbitrary when they are mixed.

[0014] The ablation-resistant resin is selected from one or two of phenolic resin, polyimide resin and furfural resin, and the ratio of two resins is 1:1 to 1:3 when they are mixed.

[0015] The reinforcing agent is selected from one or both of fumed silica and precipitated silica, and the mixture is in any proportion.

[0016] The active diluent monomer is selected from one or both of 6-hexanediol diacrylate and epoxy acrylate, and the mixture is in any proportion.

[0017] The photoinitiator is selected from 2-hydroxy-2-methyl-1-phenyl-1-propanone;

[0018] The plasticizer is selected from one of dibutyl phthalate, dioctyl phthalate, and dioctyl sebacate.

[0019] Furthermore, the fiber filler has a length of 1mm-3mm, and the fiber filler is pre-coated with type III hydroxyl-terminated polybutadiene or epoxy resin for surface treatment.

[0020] The above-mentioned method for preparing a solid engine thermo-photocurable insulation-lining material includes the following steps:

[0021] S1: Prepare the components of the solid engine thermal / photocurable insulation / lining material. According to the mass percentage, add the various additives of the solid engine thermal / photocurable insulation / lining material to the remote claw type epoxy acrylate phosphate resin, and mix them evenly with a pneumatic agitator to obtain the solid engine thermal / photocurable insulation / lining slurry.

[0022] S2: Place the uniformly mixed solid engine heat / light curing insulation / lining slurry obtained in S1 into the engine housing, keep the housing rotating at a speed of 50-100 rpm, and use a silicone rubber sheet to uniformly scrape and form it.

[0023] S3: Select an ultraviolet light source with a wavelength of 200μm-350μm and irradiate the solid engine thermal / photocurable insulation / lining slurry obtained in step S2 for 5min-20min.

[0024] S4: The solid engine thermal / photocurable insulation / lining slurry, which has been pre-cured by UV light in S3, is loaded with hydroxyl propellant. The solid engine thermal / photocurable insulation / lining and propellant are cured at a temperature of 50℃-70℃ and a curing time of 3d-7d to obtain the solid engine thermal-photocurable insulation-lining material.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The solid engine heat-curing insulation-lining material of the present invention is formulated by combining the characteristics of heat / light curing matrix resin and designing a formula suitable for the performance requirements of insulation layer and lining. It has the properties of ablation resistance, mechanical properties, adhesion and curing properties, and can solve the problems of low interfacial bonding strength, bulging and weak adhesion caused by the different resin systems of traditional rubber-based insulation materials and hydroxyl-butadiene lining.

[0027] 2. The method for preparing a solid rocket motor thermal-photocurable insulation-liner material described in this invention achieves initial pre-curing through ultraviolet light curing, ensuring that the initial strength of the insulation / liner material meets the requirements of the propellant loading vacuum process. At the same time, it retains isocyanate groups or epoxy and other active groups, which react with active hydrogen or isocyanate groups in hydroxyl propellant to achieve "chemical bonding" at the bonding interface, ensuring the bonding strength of the solid rocket motor interface and significantly reducing the cycle of engine insulation fabrication and liner coating.

[0028] 3. Existing hydroxyl-butyl liner materials require a "semi-cured" state during the propellant coating process to meet vacuuming and bonding performance requirements. However, due to limitations in testing technology and environmental factors, accurate testing of the semi-cured state is currently impossible, making the determination of the semi-cured state quite difficult. In contrast, the solid propellant engine thermo-photocurable insulation-liner material described in this invention regulates the degree of cross-linking of the photocurable resin by adjusting its molecular weight, addition amount, and photocuring parameters. This allows for quantitative and quantitative pre-curing of the insulation / liner material, achieving precise semi-curing of the thermo-photocurable liner material. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the sample after thermal / photocuring insulation / oxyacetylene ablation of the solid propellant grain in Experimental Example 1 of this invention. Detailed Implementation

[0030] The present invention will be further described in detail below through embodiments, but these embodiments should not be considered as limiting the present invention.

[0031] A solid engine thermo-photocurable insulation-lining material, comprising the following components by mass percentage:

[0032] Table 1 shows the formulation composition ratios of the thermo / photocurable liner material in different implementation cases:

[0033]

[0034] Example 1:

[0035] A method for preparing a solid engine thermo-photocurable insulation-lining material includes the following steps:

[0036] According to the heat / light curing insulation / lining formulation ratio, each additive is added to the remote claw type epoxy acrylate phosphate resin. The mixture is mixed using a pneumatic agitator. The uniformly mixed slurry is placed on the inner wall of the engine housing, which is rotated at 70 rpm. The mixture is then uniformly coated using a silicone rubber sheet. The mixture is irradiated with a 200 μm ultraviolet light source for 20 minutes. After pre-curing, the propellant loading operation is carried out. The curing temperature of the insulation / lining material and the propellant is 50℃, and the curing time is 7 days.

[0037] Figure 1 This is a schematic diagram of the sample after thermal / photocuring insulation / oxyacetylene ablation of the solid propellant grain in Experiment Example 1.

[0038] Example 2:

[0039] A method for preparing a solid engine thermo-photocurable insulation-lining material includes the following steps:

[0040] According to the heat / light curing insulation / lining formulation ratio, each additive is added to the remote claw type epoxy acrylate phosphate resin. The mixture is mixed using a pneumatic agitator. The uniformly mixed slurry is placed on the inner wall of the engine housing, which is rotated at 100 rpm. The mixture is then uniformly coated using a silicone rubber sheet. The mixture is irradiated with a 350 μm ultraviolet light source for 5 minutes. After pre-curing, the propellant loading operation is carried out. The curing temperature of the insulation / lining material and the propellant is 70℃, and the curing time is 3 days.

[0041] Example 3:

[0042] A method for preparing a solid engine thermo-photocurable insulation-lining material includes the following steps:

[0043] According to the heat / light curing insulation / lining formulation ratio, each additive is added to the remote claw type epoxy acrylate phosphate resin. The mixture is mixed using a pneumatic agitator. The uniformly mixed slurry is placed on the inner wall of the engine housing, which is rotated at 50 rpm. The mixture is then uniformly coated using a silicone rubber sheet. The mixture is irradiated with a 300 μm ultraviolet light source for 10 minutes. After pre-curing, the propellant loading operation is carried out. The curing temperature of the insulation / lining material and the propellant is 60℃, and the curing time is 5 days.

[0044] Example 4:

[0045] A method for preparing a solid engine thermo-photocurable insulation-lining material includes the following steps:

[0046] According to the heat / light curing insulation / lining formulation ratio, each additive is added to the remote claw type epoxy acrylate phosphate resin. The mixture is mixed using a pneumatic agitator. The uniformly mixed slurry is placed on the inner wall of the engine housing, which is rotated at 80 rpm. The mixture is then uniformly coated using a silicone rubber sheet. The mixture is irradiated with a 250 μm ultraviolet light source for 16 minutes. After pre-curing, the propellant loading operation is carried out. The curing temperature of the insulation / lining material and the propellant is 70℃, and the curing time is 3 days.

[0047] Comparative Example 1 (EPDM insulation material):

[0048] Ethylene propylene diene monomer (EPDM) rubber is mixed and permeated with silica reinforcing agent, phenolic resin, fiber filler, plasticizer, sulfur and vulcanizing agent using an internal mixer and a two-roll mill. The vulcanized samples are then subjected to ablation, mechanical and steel interface adhesion strength tests.

[0049] Comparative Example 2 (hydroxyl-butyl liner material):

[0050] Hydroxyl-terminated polybutadiene adhesive was mixed with crosslinking agent, curing agent, plasticizer, solid filler and other ingredients to prepare hydroxyl-terminated butadiene liner material. After the sample was cured, ablation, mechanical and propellant interfacial bonding strength tests were performed.

[0051] Table 2 shows the performance test results of the solid-fuel engine thermo-photocurable insulation-lining materials in Implementation Cases 1-4 and Comparative Examples 1-2:

[0052]

[0053] The results show that:

[0054] 1. Through comparison of Examples 1-4 and Comparative Example 1, it is demonstrated that the thermo-photocurable insulation-lining material of the present invention has good adhesion performance to the propellant interface, with an oxy-acetylene ablation rate of 0.16-0.24 mm / s (25s), a tensile strength of 5.21-6.57 MPa, an elongation at break of 246-323%, a propellant interface adhesion strength of 0.78-0.85 MPa, and a steel interface adhesion strength of 3.09-3.42 MPa; it eliminates the need for a traditional hydroxyl-butadiene lining as the interface bonding layer between the propellant and the insulation material, while maintaining performance essentially equivalent to that of rubber insulation materials.

[0055] 2. By comparing Examples 1-4 and Comparative Example 2, it is shown that the propellant bonding performance of the thermo-cured heat insulation-lining material and the hydroxyl-butyl lining of the present invention is comparable, and it can be directly used as the bonding layer between the propellant and the heat insulation layer. At the same time, the thermo-cured heat insulation-lining material has good ablation resistance and mechanical properties.

[0056] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Various process solutions that are not substantially different from the concept of the present invention are all within the scope of protection of the present invention.

Claims

1. A solid engine thermo-photocurable insulation-lining material, characterized in that: It is made from the following components by weight percentage: The composition includes: 40%-60% telescopic epoxy acrylate phosphate resin, 10%-20% fiber filler, 5%-10% adhesive, 5%-15% ablation resistant resin, 8%-12% reinforcing agent, 2%-5% reactive diluent monomer, 2%-3% photoinitiator, and 3%-5% plasticizer; The molecular weight of the telechelic epoxy phosphate resin is one or more of 3000, 5000 and 7000; The fiber filler is selected from one or two of basalt fiber, high silica fiber and alumina fiber. The fiber filler has a length of 1mm-3mm and is pre-coated with type III hydroxyl-terminated polybutadiene or epoxy resin. The adhesive is selected from one or two of type III hydroxyl-terminated polybutadiene and epoxy resin; The ablation-resistant resin is selected from one or two of phenolic resin, polyimide resin and furfural resin; The reinforcing agent is selected from one or both of fumed silica and precipitated silica; The active diluent monomer is selected from one or both of 6-hexanediol diacrylate and epoxy acrylate; The photoinitiator is selected from 2-hydroxy-2-methyl-1-phenyl-1-propanone; The plasticizer is selected from one of dibutyl phthalate, dioctyl phthalate, and dioctyl sebacate.

2. The preparation method of a solid engine thermo-photocurable insulation-lining material according to claim 1, characterized in that: Includes the following steps: S1: Prepare the components of the solid engine thermal / photocurable insulation / lining material. According to the mass percentage, add the various additives of the solid engine thermal / photocurable insulation / lining material to the remote claw type epoxy acrylate phosphate resin, and mix them evenly with a pneumatic agitator to obtain the solid engine thermal / photocurable insulation / lining slurry. S2: Place the uniformly mixed solid engine heat / light curing insulation / lining slurry obtained in S1 into the engine housing, keep the housing rotating at a speed of 50-100 rpm, and use a silicone rubber sheet to uniformly scrape and form it. S3: Select an ultraviolet light source with a wavelength of 200nm-350nm and irradiate the solid engine thermal / photocurable insulation / lining slurry obtained in step S2 for 5min-20min. S4: The solid engine thermal / photocurable insulation / lining slurry, which has been pre-cured by UV light in S3, is loaded with hydroxyl propellant. The solid engine thermal / photocurable insulation / lining and propellant are cured at a temperature of 50℃-70℃ and a curing time of 3d-7d to obtain the solid engine thermal-photocurable insulation-lining material.

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