Lightweight high-heat-resistant epoxy resin for wet winding of engine housing carbon fiber

Abstract

The present application relates to a kind of light high heat-resistant epoxy resin for carbon fiber wet winding of engine shell, including modified hollow nanometer silica particles and epoxy resin, the particle size of the hollow nanometer silica particles is 10-30nm, the hollow pore size of modified hollow nanometer silica particles is 5-20nm.The present application uses the specific size of silica nanoparticle of high rigidity and heat-resistant epoxy system chemical bonding, the scale synergistic effect of nanoparticle can further improve the heat resistance of epoxy resin;Specifically, from the research of the present application, when the particle size of silica is less than 10nm cannot be made into hollow structure;When its particle size is 10-30nm, there is good dispersibility, and when hollow pore size is 5-20nm, it has good dispersibility also has good true density, so as to further improve the heat resistance of epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of solid rocket motors, and in particular to a lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber in engine casings. Background Technology

[0002] To improve engine efficiency and reduce negative mass, large-sized solid rocket motors are generally manufactured using a wet winding process, typically employing epoxy resin systems. However, conventional epoxy resin systems have low heat resistance, and their performance rapidly degrades under the aerodynamic heat of rocket flight, affecting the overall safety of the engine. The application of curing systems combining multifunctional aromatic epoxy resins with aromatic polyamines is an effective means to improve the heat resistance of wet-wound epoxy resins. Because these systems contain a large number of high-stiffness benzene rings and have a high degree of crosslinking, they exhibit high heat resistance. However, due to the high degree of crosslinking, their density is also high; currently, the density of high-temperature wet-wound resin systems used in solid rocket motor casings is typically around 1.2 g / cm³. 3 The above significantly increases the negative mass of the engine and reduces the payload capacity of solid rockets. Summary of the Invention

[0003] This invention aims to solve the problem of difficulty in coordinating the process performance, heat resistance, and low density of epoxy resins used in existing wet winding processes. It provides a lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber engine casings, which can simultaneously improve the heat resistance of solid rocket engine casings and reduce their negative mass, thereby enhancing their carrying capacity.

[0004] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows: a lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber for engine housing, comprising modified hollow nano-silica particles and epoxy resin, wherein the particle size of the hollow nano-silica particles is 10-30 nm.

[0005] Furthermore, the mass ratio of the modified hollow nano-silica particles to the epoxy resin is 5-20:100.

[0006] Furthermore, the modified hollow nano-silica particles have a hollow pore size of 5-20 nm.

[0007] Furthermore, the modification method of the modified hollow nano silica particles is as follows: the hollow nano silica particles are dispersed in an alcohol-water system, and an epoxy silane coupling agent or an amino silane coupling agent is added at 0-100℃, and the mixture is stirred for 1-24 hours.

[0008] Furthermore, the epoxy silane coupling agent includes any one or a combination of more than one of epoxypropyltrimethoxysilane, epoxypropyltriethoxysilane, epoxytrimethoxysilane, and epoxytriethoxysilane.

[0009] Furthermore, the aminosilane coupling agent includes any one or a combination of more than one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethyltrimethoxysilane, and aminoethyltriethoxysilane.

[0010] Furthermore, the epoxy resin is a combination of a multifunctional aromatic epoxy resin and a multifunctional epoxy diluent.

[0011] The multifunctional aromatic epoxy resin includes one or more of the following: 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85), trifunctional amino epoxy resin (AFG-90), and tetraglycidylamine epoxy resin (AG-80).

[0012] The polyfunctional epoxy diluent includes one or more of ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0013] Further, the method for preparing the hollow nano-silica particles is as follows: citric acid is dissolved in a mixed solution of H2O and ethanol, FeCl3 is added, the molar ratio of citric acid to FeCl3 is 2:(1-12), the pH of the solution is adjusted to 8-11, then resorcinol and formaldehyde are added, and the mixture is stirred. Anhydrous ethanol, ammonia and tetraethyl orthosilicate are then added to the system, and the mixture is stirred. The product is separated by centrifugation, washed with an acid solution, and then washed with water to remove the acid, yielding particulate product. The obtained particulate product is vacuum dried to obtain hollow nano-silica particles with a particle size of 10-30 nm and a hollow pore size of 5-20 nm.

[0014] Furthermore, after adding FeCl3, the pH of the solution was adjusted to 9.5-10.5.

[0015] The present invention also provides a solid rocket motor housing, comprising a lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber as described above.

[0016] Compared with the prior art, the method of the present invention has the following advantages and beneficial effects:

[0017] 1. By chemically bonding high-rigidity silica nanoparticles of a specific size with a heat-resistant epoxy system, the scale synergy effect of the nanoparticles can further improve the heat resistance of the epoxy resin. Specifically, according to the research of this invention, when the silica particle size is less than 10 nm, it cannot be made into a hollow structure; when its particle size is 10-30 nm, it has good dispersibility, and when the hollow pore size is 5-20 nm, it has both good dispersibility and good true density, thereby further improving the heat resistance of the epoxy resin.

[0018] 2. By using hollow silica nanoparticles, the heat resistance of epoxy resin is improved while its density is reduced, thereby reducing the negative weight of the solid rocket motor casing.

[0019] 3. The addition of spherical nanoparticles of a certain particle size can maintain the processability of high heat-resistant epoxy resin, thus making this modification method suitable for the wet winding process of carbon fiber, ensuring the operability of wet winding of carbon fiber shells for solid rocket engines. Attached Figure Description

[0020] Figure 1 SEM image of hollow silica nanoparticles prepared in Example 2 of this invention;

[0021] Figure 2 This is a SEM image of the hollow silica nanoparticles prepared in Example 3 of the present invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Hollow nano-silica is a type of functional nanomaterial with a hollow core-shell structure, widely used in fields such as drug sustained release, controlled catalysis, and thermal / electrical insulation. It is characterized by its lightweight, high structural rigidity, and high heat resistance. At the same time, by controlling its particle size within a certain range, the processing properties (viscosity and reactivity) of the polymer host material can be maintained. Therefore, after surface modification, it can be applied to occasions with extremely demanding requirements for heat resistance, weight, and processability. It is particularly suitable for carbon fiber wound shells of solid rocket engines and can also be used for composite material nozzle shells of solid rocket engines.

[0024] Example 1

[0025] The present invention discloses a lightweight, high-heat-resistant epoxy resin for wet-winding carbon fiber in engine housings. The process mainly involves preparing hollow-structured nano-silica particles, modifying the hollow-structured nano-silica particles, and uniformly dispersing the surface-modified nano-particles in an epoxy resin, thereby preparing a lightweight, high-heat-resistant wet-winding epoxy resin. The specific steps are as follows:

[0026] S1. Dissolve 0.17 mmol of citric acid in a mixed solution of 15 ml H2O and 12 ml ethanol, and simultaneously add 0.1 mmol FeCl3. Adjust the pH of the solution to 10 with ammonia, then add 0.2 g resorcinol and 0.28 ml formaldehyde, and stir for 10 h. Continue to add 40 ml anhydrous ethanol, 0.8 ml ammonia, and 0.75 ml tetraethyl orthosilicate to the system, and stir for another 10 h. Centrifuge the product, wash four times with 0.1 mol / L HCl solution, and then wash with water to remove acid, obtaining particulate product. Vacuum dry the obtained particulate product for 6 h to obtain hollow nano-SiO2 particles with an average particle size of 27 nm and an average pore size of 18 nm. The iron ions in the solution undergo a strong coordination reaction with the carboxyl groups of citric acid, thereby reducing the influence of oligomers in the resin and decreasing the microsphere size. The iron ions form a stable bond with the carboxyl groups, which weakens their adsorption of silica particles and reduces the aggregation of silica particles; thus, silica with the desired size is prepared.

[0027] S2. Weigh 1g of hollow nano-SiO2 and add it to 25ml of toluene. Disperse the mixture using an ultrasonic cleaner (300W) at room temperature for 30min to obtain a uniform suspension. Then add 0.364g of epoxy-containing silane coupling agent KH-560, i.e., glycidyltrimethoxysilane, to the suspension and mix ultrasonically for 5min. Then react in a constant temperature bath at 90℃ for 6h. Centrifuge the resulting reaction solution at room temperature at 12000r / min to obtain modified hollow nano-SiO2. Centrifuge 6 times ultrasonically and vacuum dry for 8h to obtain a white powder, i.e., epoxy-containing hollow nano-SiO2.

[0028] S3. The modified hollow nano-SiO2 particles were uniformly dispersed in a mixture of TDE-85 epoxy resin and AG-80 resin (ratio of 1.5:1) at a mass ratio of 10:100 (silica particles and epoxy resin), and in a combination with the polyfunctional epoxy diluent ethylene glycol diglycidyl ether. The curing agent was m-phenylenediamine, thus preparing a lightweight, high-heat-resistant wet-wrapped epoxy resin.

[0029] Without the addition of modified hollow nano-SiO2, the Martin heat resistance temperature of TDE-85 epoxy resin and m-phenylenediamine curing agent is 185℃, and the density is 1.406 g / cm³. 3 The viscosity is 1600-2000 mPa·s (at 25℃), while the heat resistance temperature of Martin can reach 200℃ after adding modified hollow nano-SiO2, and the density is reduced to 1.062 g / cm³. 3 The viscosity is 1800-2200 mPa·s (at 25℃), which increases slightly, but can be ignored in actual operation.

[0030] Example 2:

[0031] The present invention discloses a lightweight, high-heat-resistant epoxy resin for wet-winding carbon fiber in engine housings. The process mainly involves preparing hollow-structured nano-silica particles, modifying the hollow-structured nano-silica particles, and uniformly dispersing the surface-modified nano-particles in an epoxy resin, thereby preparing a lightweight, high-heat-resistant wet-winding epoxy resin. The specific steps are as follows:

[0032] S1. Dissolve 0.17 mmol of citric acid in a mixed solution of 15 ml H2O and 15 ml methanol and ethanol (methanol to ethanol ratio 1:3), and simultaneously add 0.3 mmol FeCl3. Adjust the pH of the solution to 10 with ammonia water, then add 0.2 g resorcinol and 0.28 ml formaldehyde, and stir for 10 h. Continue to add 50 ml anhydrous ethanol, 0.8 ml ammonia water, and 0.75 ml tetraethyl orthosilicate to the system, and stir for 10 h. Centrifuge the product, wash it four times with 0.1 mol / L HCl solution, and then wash it with water to remove acid, obtaining particulate product. Vacuum dry the obtained particulate product for 6 h to obtain hollow nano-SiO2 particles with an average particle size of 20 nm and an average pore size of 15 nm. Figure 1 Here is its electron microscope image.

[0033] S2. Weigh 2g of hollow nano-SiO2 and add it to 50ml of toluene. Disperse the mixture using an ultrasonic cleaner (300W) at room temperature for 40min to obtain a uniform suspension. Then add 0.236g of epoxy-containing silane coupling agent epoxytriethoxysilane to the suspension and mix ultrasonically for 3min. Then react in a constant temperature bath at 100℃ for 5h. Centrifuge the resulting reaction solution at room temperature at 13000r / min to obtain modified hollow nano-SiO2. Centrifuge 6 times ultrasonically and vacuum dry for 8h to obtain a white powder, namely amino-containing hollow nano-SiO2.

[0034] S3. The modified hollow nano-SiO2 particles were uniformly dispersed in AFG-90 epoxy resin and its combination with polyfunctional epoxy diluent trimethylolpropane triglycidyl ether at a mass ratio of 12:100, with m-phenylenediamine as the curing agent, to prepare a lightweight, high-heat-resistant wet-wrapped epoxy resin.

[0035] Without the addition of modified hollow nano-SiO2, the Martin heat resistance temperature of AFG-90 epoxy resin and m-phenylenediamine curing agent is 150℃, and the density is 1.22 g / cm³. 3 The viscosity is 1500-2500 mPa·s (at 25℃), while the heat resistance temperature of Martin can reach 195℃ after adding modified hollow nano-SiO2, and the density is reduced to 1.05 g / cm³. 3 The viscosity is 1600-2200 mPa·s (at 25℃), which increases slightly, but can be ignored in actual operation.

[0036] Example 3:

[0037] The present invention discloses a lightweight, high-heat-resistant epoxy resin for wet-winding carbon fiber in engine housings. The process mainly involves preparing hollow-structured nano-silica particles, modifying the hollow-structured nano-silica particles, and uniformly dispersing the surface-modified nano-particles in an epoxy resin, thereby preparing a lightweight, high-heat-resistant wet-winding epoxy resin. The specific steps are as follows:

[0038] S1. Dissolve 0.17 mmol of citric acid in a mixed solution of 15 ml H2O and 12 ml methanol and ethanol (methanol to ethanol ratio 1:4), and simultaneously add 0.5 mmol FeCl3. Adjust the pH of the solution to 10.5 with ammonia water, then add 0.2 g resorcinol and 0.28 ml formaldehyde, and stir for 10 h. Continue to add 50 ml anhydrous ethanol, 0.8 ml ammonia water, and 0.75 ml tetraethyl orthosilicate to the system, and stir for 12 h. Centrifuge the product, wash five times with 0.1 mol / L HCl solution, and then wash with water to remove acid to obtain particulate product. Vacuum dry the obtained particulate product for 10 h to obtain hollow nano-SiO2 particles with an average particle size of 16 nm and an average pore size of 10 nm. Figure 2 Here is its electron microscope image.

[0039] S2. Weigh 3g of hollow nano-SiO2 and add it to 50ml of toluene. Disperse the mixture using an ultrasonic cleaner (300W) at room temperature for 50min to obtain a uniform suspension. Then add 0.338g of amino-containing silane coupling agent aminopropyltrimethoxysilane to the suspension and mix ultrasonically for 5min. Then react in a constant temperature bath at 100℃ for 8h. Centrifuge the resulting reaction solution at room temperature at 13000r / min to obtain modified hollow nano-SiO2. Centrifuge again 8 times and vacuum dry for 10h to obtain a white powder, which is the amino-containing hollow nano-SiO2.

[0040] S3. The obtained modified hollow nano-SiO2 particles are uniformly dispersed in AG-80 epoxy resin and its combination with the polyfunctional epoxy diluent pentaerythritol tetraglycidyl ether at a mass ratio of 15:100, with diaminodiphenyl sulfone as the curing agent, to prepare a lightweight, high-heat-resistant wet-wrapped epoxy resin.

[0041] Without the addition of modified hollow nano-SiO2, the Martin heat resistance temperature of AG-80 epoxy resin and diaminodiphenylmethane curing agent is 170℃, and the density is 1.26 g / cm³. 3 The viscosity is 3000-6000 mPa·s (at 50℃), while the heat resistance temperature of Martin can reach 198℃ after adding modified hollow nano-SiO2, and the density is reduced to 1.03 g / cm³. 3The viscosity is 3000-6000 mPa·s (at 50℃).

[0042] Example 4:

[0043] This invention discloses a lightweight, high-heat-resistant epoxy resin for wet-winding carbon fiber in engine housings. The process mainly involves preparing hollow-structured nano-silica particles, modifying the hollow-structured nano-silica particles, and uniformly dispersing the surface-modified nano-particles in the epoxy resin, thereby preparing the lightweight, high-heat-resistant wet-winding epoxy resin. A common method for preparing hollow nano-silica particles is the template method, which involves a sol-gel process and a surface-protective etching strategy. The specific steps are as follows:

[0044] S1. Dissolve 0.17 mmol of citric acid in a mixed solution of 20 ml H2O and 15 ml ethanol, and add 1 mmol FeCl3. Adjust the pH of the solution to 9.5 with ammonia. Then add 0.2 g resorcinol and 0.28 ml formaldehyde, and stir for 12 h. Continue to add 50 ml anhydrous ethanol, 0.8 ml ammonia and 0.75 ml tetraethyl orthosilicate to the system, and stir for 12 h. Centrifuge the product, wash it five times with 0.1 mol / L HCl solution, and then wash it with water to remove acid to obtain particulate product. Vacuum dry the obtained particulate product for 10 h to obtain hollow nano-SiO2 particles with an average particle size of 13 nm and an average pore size of 6 nm.

[0045] S2. Weigh 5g of hollow nano-SiO2 and add it to 100ml of toluene. Disperse the mixture using an ultrasonic cleaner (300W) at room temperature for 60min to obtain a uniform suspension. Then add 0.338g of amino-containing silane coupling agent aminopropyltrimethoxysilane to the suspension and mix ultrasonically for 5min. Then react in a constant temperature bath at 100℃ for 8h. Centrifuge the resulting reaction solution at room temperature at 13000r / min to obtain modified hollow nano-SiO2. Centrifuge again 8 times and vacuum dry for 10h to obtain a white powder, which is amino-containing hollow nano-SiO2.

[0046] S3. The obtained modified hollow nano-SiO2 particles are uniformly dispersed in AG-80 epoxy resin and its combination with the polyfunctional epoxy diluent pentaerythritol tetraglycidyl ether at a mass ratio of 20:100, with diaminodiphenyl sulfone as the curing agent, to prepare a lightweight, high-heat-resistant wet-wrapped epoxy resin.

[0047] Without the addition of modified hollow nano-SiO2, the Martin heat resistance temperature of AG-80 epoxy resin and diaminodiphenylmethane curing agent is 170℃, and the density is 1.26 g / cm³. 3The viscosity is 3000-6000 mPa·s (at 50℃), while the heat resistance temperature of Martin can reach 205℃ and the density is reduced to 1.013 g / cm³ after adding modified hollow nano-SiO₂. 3 The viscosity is 3000-6000 mPa·s (at 50℃), and the viscosity range (at 50℃) is also 3000-6000 mPa·s.

[0048] Comparative Example 1:

[0049] The preparation method of this comparative example is basically the same as that of Example 1; the difference is that hollow nano-SiO2 with a particle size of 40-80 nm and a pore size of 25-60 nm is used in this comparative example; the epoxy resin obtained in this example is tested as a castable sample, and the density at the lower end of the sample is measured to be 1.18 g / cm³. 3 The density at the upper end is 1.12 g / cm³. 3 It can be seen that the hollow nano-SiO2 is not uniformly dispersed in the resin. By testing the heat resistance of the sample, it was found that its heat resistance temperature has been improved, reaching 170-185℃, but it is not as good as the improvement effect of Example 1.

[0050] Comparative Example 2:

[0051] The preparation method of this comparative example is basically the same as that of Example 1; the difference is that hollow nano-SiO2 with a particle size of 10-30 nm and a pore size of 3-5 nm is selected; the final epoxy resin is tested by casting specimen testing, and the density of the lower end of the casting specimen is 1.148 g / cm³. 3 The density at the upper end is 1.113 g / cm³. 3 Its heat resistance and the heat resistance temperature of the resin-based product differ by 5-10℃, with no significant change.

[0052] As can be seen from Comparative Examples 1 and 2, modifying epoxy resin with hollow nano-SiO2 of other sizes does not reduce density as effectively as in Example 1 of this invention, and there is a problem of uneven dispersion of SiO2 in the resin. Comparative Examples 1 and 2 also do not provide ideal improvement in the resin's heat resistance, and may even have no effect. Furthermore, when the SiO2 particle size is less than 10 nm, a hollow structure cannot be formed; when the SiO2 pore size and particle size difference are less than 5 nm, the core and shell are prone to breakage during ultrasonic mixing and centrifugation, leading to the destruction of the hollow structure. This indicates that the present invention, by selecting hollow nano-SiO2 with specific particle and pore sizes, can effectively reduce resin density and produce a scale synergistic effect with the epoxy resin system, further improving the resin's heat resistance.

[0053] The method of this invention uses hollow-structured nano-silica particles as additives, which are uniformly dispersed into epoxy resin after surface chemical modification. They are then chemically bonded with high-functionality aromatic epoxy and aromatic amine curing agents to prepare a high-heat-resistant, low-density epoxy resin. With the help of special curing agents, it can be applied to the wet winding molding of carbon fiber shells for solid rocket engines, improving the heat resistance of the carbon fiber shell while reducing its negative mass, thereby improving the mass ratio of the rocket engine and increasing its carrying capacity. It can also be extended to applications such as composite material nozzle shells for solid rocket engines where the requirements for weight, heat resistance, and processability are extremely stringent.

Claims

1. A lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber in engine housings, characterized in that... The product comprises modified hollow nano-silica particles and epoxy resin, wherein the mass ratio of the modified hollow nano-silica particles to the epoxy resin is (5-20):100, the epoxy resin is a combination of a multifunctional aromatic epoxy resin and a multifunctional epoxy diluent, the particle size of the modified hollow nano-silica particles is 10-30 nm, the hollow pore size of the modified hollow nano-silica particles is 5-20 nm, and the difference between the pore size and the particle size is not less than 5 nm. The modification method of the modified hollow nano silica particles is as follows: the hollow nano silica particles are dispersed in an alcohol-water system, and an epoxy silane coupling agent or an amino silane coupling agent is added at 0-100℃, and the mixture is stirred for 1-24 hours. The hollow nano-silica particles are prepared as follows: Citric acid is dissolved in a mixed solution of H2O and ethanol, FeCl3 is added, the molar ratio of citric acid to FeCl3 is 2:(1-12), the pH of the solution is adjusted to 9.5-10.5, then resorcinol and formaldehyde are added, stirred, and then anhydrous ethanol, ammonia and tetraethyl orthosilicate are added, and stirred. The product was separated by centrifugation, washed with acid solution, and then washed with water to remove the acid, resulting in particulate product. The obtained particulate product was vacuum dried to obtain hollow silica nanoparticles with a particle size of 10-30 nm, a hollow pore size of 5-20 nm, and a difference between the pore size and the particle size of not less than 5 nm.

2. The lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber in engine housings according to claim 1, characterized in that... The epoxy silane coupling agent includes any one or a combination of more than one of epoxypropyltrimethoxysilane, epoxypropyltriethoxysilane, epoxytrimethoxysilane, and epoxytriethoxysilane.

3. The lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber in engine housings according to claim 1, characterized in that... The aminosilane coupling agent includes any one or a combination of more than one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethyltrimethoxysilane, and aminoethyltriethoxysilane.

4. The lightweight, high-heat-resistant epoxy resin for wet winding of carbon fiber in engine housings according to claim 1, characterized in that... The epoxy resin is a combination of a multifunctional aromatic epoxy resin and a multifunctional epoxy diluent. The multifunctional aromatic epoxy resin includes one or more of the following: 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, trifunctional amino epoxy resin, and tetraglycidylamine epoxy resin. The polyfunctional epoxy diluent includes one or more of ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

5. A solid rocket motor casing, characterized in that, The epoxy resin for wet winding of carbon fiber in engine housings as described in any one of claims 1-4 is a lightweight, high-heat-resistant epoxy resin.

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