A resin system for low-temperature-resistant pre-impregnated filaments of low-temperature high-pressure hydrogen storage cylinders

Abstract

The application relates to the technical field of composite materials, and discloses a resin system for low-temperature-resistant prepreg filaments of low-temperature high-pressure hydrogen storage cylinders, wherein the resin system comprises the following components in parts by weight: 100 parts of a composite resin matrix, 25-60 parts of a composite curing agent, 1-2 parts of an accelerator and 2-20 parts of a composite toughening agent; wherein the composite toughening agent is obtained by mixing a flexible polymer and nanoparticles at a weight ratio of 1-20:1-10; the flexible polymer is at least one selected from polyether block polymers L-61, polyether amines and polyamides, and the molecular weight of the flexible polymer is greater than 1500; and the nanoparticles are at least one selected from silicon dioxide, graphene, SiO2 / PU core-shell particles and SiO2 / PMMA core-shell particles. The technical scheme provided by the application can provide the resin system for dry-winding prepreg filaments which takes into account the toughness and strength.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of composite materials, and in particular to a resin system for low-temperature-resistant prepreg filaments of low-temperature high-pressure hydrogen storage cylinders. BACKGROUND

[0002] Hydrogen energy, as a clean and efficient energy, has the potential to reduce greenhouse gas emissions and be widely used in transportation, industry and energy storage. However, the low-temperature high-pressure hydrogen storage technology (CcH2) faces challenges in safety and efficiency of storage and transportation. In the design of low-temperature compression hydrogen storage containers, the outer fiber composite material bears the main load-bearing function, and its performance has a decisive influence on the overall safety of the container. Dry winding technology has a good application prospect in the manufacturing of such structures due to its high product quality, high production efficiency and small environmental impact. However, the lack of low-temperature toughening resin systems limits its application, especially the brittleness of epoxy resin at low temperature, which is difficult to meet the performance requirements of hydrogen storage containers. SUMMARY

[0003] The application provides a resin system for low-temperature-resistant prepreg filaments of low-temperature high-pressure hydrogen storage cylinders, which achieves the technical effect of balancing toughness and strength.

[0004] In order to achieve the above-mentioned purpose, the main technical scheme adopted by the application includes:

[0005] In a first aspect, the application provides a resin system, which includes the following components by weight: 100 parts of a composite resin matrix, 25-60 parts of a composite curing agent, 1-2 parts of an accelerator, and 2-20 parts of a composite toughening agent; wherein the composite toughening agent is obtained by mixing a flexible polymer and nanoparticles in a weight ratio of 1-20:1-10; the flexible polymer is selected from at least one of polyether block polymer L-61, polyether amine and polyamide, and the molecular weight of the flexible polymer is greater than 1500; and the nanoparticles are selected from at least one of silicon dioxide, graphene, SiO2 / PU core-shell particles and SiO2 / PMMA core-shell particles.

[0006] The composite resin matrix in this embodiment is the main structural framework, which determines the basic properties of the resin system with high thermal stability and mechanical strength. The accelerator cooperates to control the rate of curing reaction. By adjusting the curing rate, premature curing can be avoided, and the flowability of the resin system during processing can be maintained. In particular for processes such as prepreg filaments, controlling the timing and rate of curing is very important, which ensures the consistency and reliability of the resin system under different operating conditions. The addition of composite toughening agent significantly improves the toughness of the resin system at low temperature. At low temperature, the resin usually becomes more brittle and is prone to crack propagation. After adding the composite toughening agent, a solid multiple interpenetrating polymer network (IPN) structure is formed, and the crosslinked network framework is stretched and slipped through the flexible network formed by flexible polymer molecular chains to absorb impact energy, which can delay crack propagation. Since the molecular weight of the flexible polymer in the composite toughening agent is greater than 1500, it indicates that it has sufficient chain length and movement ability, and can still effectively absorb impact force even in a low temperature environment.

[0007] Specifically, flexible polymers such as polyether block polymers L-61, polyether amines, polyamides, etc. can form a multiple interpenetrating polymer network (IPN) structure with the composite resin matrix, strengthen the interfacial bonding force of the composite resin matrix, and provide a flexible buffer layer. This structure not only enhances the low-temperature toughness of the resin system, but also improves the mechanical strength of the resin system. The hydrogen bonding of polyamide further reduces the brittleness of the resin system in a low temperature environment and reduces the molecular chain breakage. The addition of nanoparticles (such as SiO2, graphene, etc.) enhances the strength and thermal stability of the resin system. Rigid nanoparticles such as silica help maintain the glass transition temperature (Tg) of the resin system by limiting the excessive movement of molecular chains at high temperatures, improving thermal stability. At the same time, nanoparticles can deflect or passivate cracks, increase energy dissipation for crack propagation, and further enhance the crack resistance of the material. SiO2 / PU core-shell particles or SiO2 / PMMA core-shell particles in the resin system enhance the modulus of the composite resin matrix through their inner core (rigid SiO2), and the shell part (PU or PMMA) helps to form a gradient interface in the composite resin matrix, disperses stress concentration, and reduces the risk of crack propagation. Due to the uniqueness of the core-shell particle structure, it can improve the strength while avoiding the brittleness of the rigid material in the composite resin matrix. Therefore, flexible polymers provide low-temperature toughness, and nanoparticles enhance the strength, thermal stability, and crack resistance of the resin. This "hard and soft" toughening mechanism can not only ensure the toughness of the resin system in a low temperature environment, but also ensure its strength and stability under high temperature or load conditions.

[0008] In one embodiment, the composite resin matrix is ​​obtained by mixing resin A and resin B in a weight ratio of 70-90:10-30; resin A is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and liquid phenolic resin; and resin B is selected from at least one of alicyclic epoxy resin and flexible side-chain epoxy resin.

[0009] In this embodiment, resin A is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and liquid phenolic resin. Bisphenol A epoxy resin and bisphenol F epoxy resin have high crosslinking density and mechanical strength, and low shrinkage after curing, making them suitable for applications requiring high strength and high modulus in low-temperature, high-pressure hydrogen storage cylinders. Liquid phenolic resin provides high adhesion and good chemical resistance while reducing internal stress during curing. These resins A form a dense network structure during curing, enabling them to form good interfacial bonding with reinforcing fibers (such as carbon fibers), thus improving the overall performance of the material.

[0010] Resin B is selected from at least one of alicyclic epoxy resins and flexible side-chain epoxy resins. In the alicyclic epoxy resin (such as EHPE-3150), the epoxy groups are directly attached to the alicyclic rings, forming a rigid molecular structure with a high glass transition temperature (Tg) while maintaining a certain degree of toughness at low temperatures. Allyl glycidyl ether significantly reduces internal stress during curing by introducing flexible segments, thereby improving the low-temperature toughness of the composite resin matrix. These resins B have low viscosity, enabling them to maintain good flowability at low temperatures, facilitating fiber impregnation and molding processes.

[0011] Therefore, by reasonably controlling the ratio of resin A to resin B (70-90:10-30), a balance can be achieved between high strength, low shrinkage, high adhesion and low temperature toughness, and high fluidity, thereby meeting the comprehensive performance requirements of the final resin system under various complex working conditions.

[0012] In one embodiment, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, and E42 epoxy resin; the bisphenol F epoxy resin is selected from at least one of YDF-161H epoxy resin and YDF-170 epoxy resin; the liquid phenolic resin is selected from at least one of F-51 phenolic resin and F-44 phenolic resin; the alicyclic epoxy resin is selected from at least one of EHPE-3150 resin, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarbamate; and the flexible side-chain epoxy resin is allyl glycidyl ether.

[0013] The bisphenol A epoxy resin in the embodiment is selected from at least one of E51 epoxy resin, E44 epoxy resin and E42 epoxy resin, has high crosslinking density and mechanical strength, low shrinkage after curing, higher glass transition temperature (Tg), and can provide good chemical resistance and low shrinkage in the composite resin matrix, and ensure that the material forms a stable structure during curing. The bisphenol F epoxy resin is selected from at least one of YDF-161H epoxy resin and YDF-170 epoxy resin, has lower viscosity and higher glass transition temperature (Tg). The alicyclic epoxy resin is selected from at least one of EHPE-3150 resin, bis(7-oxabicyclo[4.1.0]3-heptamethyl) adipate and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylmethyl carboxylate, has higher glass transition temperature (Tg) and good low-temperature toughness, low shrinkage after curing, and is suitable for composite materials in low-temperature and high-pressure environments, such as hydrogen storage cylinders, aerospace structural parts and the like. The flexible side chain epoxy resin is allyl glycidyl ether, has good low-temperature toughness and low viscosity, and ensures that the material still maintains good performance in a low-temperature environment. By reasonably selecting and mixing these resins, a balance between high strength, high toughness, high heat resistance and low-temperature performance of the composite material can be achieved.

[0014] In one embodiment, the composite curing agent is obtained by mixing curing agent A and curing agent B in a weight ratio of 5-30:12-40; the curing agent A is a latent amine curing agent; wherein the latent amine curing agent is selected from at least one of dicyandiamide, isophorone diamine, 1,2-cyclohexanediamine, diaminodiphenylmethane, diaminodiphenyl sulfone and m-phenylenediamine; the curing agent B is an acid anhydride curing agent; wherein the acid anhydride curing agent is selected from at least one of methyl nadic anhydride, phthalic anhydride and hexahydrophthalic anhydride.

[0015] The curing agent A in the embodiment is a latent amine curing agent, which has latency at low temperature, can be activated at a proper temperature, and controls the rate of curing reaction. This enables the resin system to be slowly cured at low temperature, avoiding premature curing.

[0016] The curing agent B is selected from at least one of methyl nadic anhydride, phthalic anhydride and hexahydrophthalic anhydride, forms a high glass transition temperature (Tg) crosslinking network during curing, and improves the thermal stability and mechanical properties of the resin system.

[0017] Therefore, by mixing the curing agent A and the curing agent B in a weight ratio of 5-30:12-40, the processability of the resin system in a low-temperature environment is ensured, and the rheological properties of the resin system are optimized, adapting to the dry winding process.

[0018] In one embodiment, the accelerator is selected from at least one of organic urea type accelerator, tertiary amine type accelerator, boron amine complex; wherein the organic urea type accelerator is selected from at least one of UR200, UR300, UR500; the tertiary amine type accelerator is selected from at least one of DMP-30, BDMA.

[0019] The main role of the accelerator in the embodiment is to accelerate the rate of curing reaction, reduce the curing temperature, shorten the curing time, and thus improve the production efficiency. By selecting a suitable accelerator, the curing efficiency of the epoxy resin system can be significantly improved, the curing temperature can be reduced, and the curing time can be shortened.

[0020] In a second aspect, the embodiment of the present application provides a resin system preparation method of the resin system described above, and the resin system preparation method comprises:

[0021] Mixing resin A and resin B, heating to 60-100℃ and mixing at a speed of 200-1000 rpm for 10-20 min to obtain a composite resin matrix;

[0022] Mixing curing agent A and curing agent B, heating to 40-80℃ and mixing at a speed of 500-800 rpm for 15-20 min to obtain a composite curing agent;

[0023] Mixing the flexible polymer and the nanoparticles, heating to 80-160℃ and mixing at a speed of 1500-2000 rpm for 10-20 min to obtain a composite toughening agent;

[0024] Mixing the composite resin matrix, the composite curing agent, the composite toughening agent and the accelerator, heating to 60-100℃ and mixing for 20-30 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain the resin system.

[0025] The mixing of resin A and resin B in this embodiment can integrate the advantages of both. Resin A provides high strength and low shrinkage, while resin B provides low temperature toughness and high flowability. Heating to 60-100°C can reduce the viscosity of the resin, making it easier to mix uniformly. Mixing at a speed of 200-1000 rpm for 10-20 min ensures that the two resins are fully mixed to form a uniform composite resin matrix. Curing agent A provides latent curing ability, which requires a certain temperature to start the curing reaction, ensuring the processability and storage stability of the resin system. Curing agent B provides high Tg and good thermal stability, while reducing the viscosity, allowing the resin system to fully infiltrate the fibers. Mixing at a speed of 500-800 rpm for 15-20 min ensures that the two curing agents are fully mixed to form a uniform composite curing agent. The addition of flexible polymer significantly improves the low temperature toughness of the resin system, ensuring that the resin system still maintains good performance in low temperature environment. The addition of nanoparticles enhances the crack resistance of the material, avoiding crack propagation. By heating and high-speed stirring, the flexible polymer and nanoparticles are fully mixed to form a uniform composite toughening agent. Mixing all components ensures that each component is fully dispersed to form a uniform resin system.

[0026] In a third aspect, the embodiments of the present application provide a prepreg preparation method, which comprises:

[0027] After the resin system is heated to 50°C in the impregnation tank, the heated resin system is uniformly laid on the release paper and fully impregnated with the reinforcing fibers to obtain a prepreg. The resin system is prepared by the resin system or the resin system preparation method described above.

[0028] The surface of the prepreg is laid with release paper, and the prepreg is pre-cured, then cooled, and the surface release paper is peeled off after cooling, and a polyethylene film is laid on the surface to obtain a prepreg.

[0029] The resin system used in this embodiment has high strength, low temperature toughness, high Tg and good process adaptability, and is suitable for the preparation of prepreg filaments. Heating to 50℃ can reduce the viscosity of the resin, making it easier to flow and impregnate the fibers. The reinforcing fibers (such as carbon fibers, glass fibers) are evenly laid on the resin, and the fibers are fully impregnated with the resin. Pre-curing is to partially cure the resin to give it a certain shape and strength, but it has not yet fully cured. This step can prevent the fibers from shifting during subsequent operations, while facilitating subsequent cooling and molding. The surface of the prepreg filament is protected by a release paper to prevent it from being contaminated or damaged during the pre-curing process. After the prepreg filament cools to room temperature, the release paper on the surface is peeled off. A layer of polyethylene film is placed on the surface of the prepreg filament. The polyethylene film can protect the surface of the prepreg filament from being contaminated or damaged during the winding process. The wound prepreg filament can be stored at room temperature for at least 60 days, with good storage stability.

[0030] In one embodiment, the pre-curing temperature is 120℃, the heating time is 20-30min, and the wound prepreg filament is stored at room temperature for at least 60 days.

[0031] This embodiment can ensure that the prepreg filament has good shape stability, thermal stability and fiber-resin bonding performance by controlling the pre-curing temperature and time. At the same time, it can be stored at room temperature for at least 60 days, and a high-performance composite material suitable for low-temperature high-pressure environment can be prepared.

[0032] In a fourth aspect, the embodiments of the present application provide an application of a prepreg filament. The prepreg filament prepared by the above-mentioned prepreg filament preparation method is applied to a low-temperature high-pressure hydrogen storage cylinder.

[0033] In one embodiment, the prepreg filament is subjected to temperature curing and cooling to obtain a low-temperature high-pressure hydrogen storage cylinder; wherein the temperature curing conditions are: 100℃ / 1h+120℃ / 1h+130℃ / 1h.

[0034] The 100℃ / 1h in this embodiment is the initial curing stage, which eliminates the original internal thermal stress. The 120℃ / 1h is the intermediate curing stage, which further enhances the crosslinking network based on the pre-curing of the prepreg filament and improves the mechanical properties of the material. The 130℃ / 1h is the post-curing stage, which ensures complete curing, and then cools to room temperature in the furnace to form a stable low-temperature high-pressure hydrogen storage cylinder. By temperature curing in stages, the rate of the curing reaction can be effectively controlled, avoiding the concentration of internal stress and the generation of defects caused by too fast curing. The gradually increasing temperature can ensure that the curing agent in the resin system fully reacts to form a high-Tg crosslinking network, improving the thermal stability of the material. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description.

[0036] Figure 1 Temperature-viscosity relationship curve of the resin system prepared for Example 1 and Comparative Example 8. DETAILED DESCRIPTION

[0037] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative labor fall within the protection scope of the present application.

[0038] Hydrogen energy, as a clean, environmentally friendly, and efficient energy form, is increasingly valued globally. It not only effectively reduces greenhouse gas emissions but also exhibits great application potential in transportation, industrial production, energy storage, and other fields. However, hydrogen storage and transportation still face many challenges, especially in terms of safety and efficiency under low-temperature and high-pressure conditions. Low-temperature compressed hydrogen storage technology (CcH2), as one of the key technologies, has a high hydrogen storage density and flexible refueling method, providing an effective solution for the promotion and application of hydrogen energy.

[0039] In the design of low-temperature compressed hydrogen storage containers, material selection is crucial. Although traditional wet winding technology is widely used, it has problems such as uneven resin impregnation, environmental pollution, and low production efficiency. Therefore, dry winding technology has gradually become an advanced process to replace wet winding, especially with significant advantages in improving production efficiency and reducing environmental pollution. Dry winding, by pre-impregnating resin in fibers, avoids the problems of resin volatilization and uneven impregnation in wet winding, thereby improving the strength and overall performance of the material.

[0040] However, although dry winding technology has potential in improving the performance of hydrogen storage materials, in the application of low-temperature and high-pressure hydrogen storage containers, there is still a lack of low-temperature toughening resin systems suitable for dry winding. Traditional epoxy resins exhibit strong brittleness in low-temperature environments, making it difficult to meet the dual demands of material toughness and strength for low-temperature and high-pressure hydrogen storage containers.

[0041] Therefore, how to provide a resin system for dry winding pre-impregnated filaments that can balance toughness and strength is a technical problem that needs to be solved at present.

[0042] In order to better explain the present application, the following is a detailed description of the present application through specific embodiments. In the embodiments, the parts are all by weight unless otherwise specified, and the raw materials in the embodiments are all purchased through commercial channels.

[0043] Example 1

[0044] The resin system of the present embodiment is prepared from the following raw materials:

[0045]

[0046] The preparation method of the resin system is as follows:

[0047] Step S1, mix E51 epoxy resin, YDF-161H epoxy resin and EHPE-3150 resin, heat to 80℃ and mix at a speed of 800 rpm for 15 min to obtain a composite resin matrix.

[0048] Step S2, mix dicyandiamide and methyl nadic anhydride, heat to 65℃ and mix at a speed of 600 rpm for 16 min to obtain a composite curing agent.

[0049] Step S3, mix polyether block polymer L-61 with SiO2 / PU core-shell particles, heat to 100℃ and mix at a speed of 1500 rpm for 15 min to obtain a composite toughening agent.

[0050] Step S4, mix the composite resin matrix, the composite curing agent, the composite toughening agent and UR500, heat to 80℃ and mix for 25 min, then ultrasonic dispersion, vacuum defoaming treatment to obtain the resin system.

[0051] Example 2

[0052] The resin system of the present embodiment is prepared from the following raw materials:

[0053]

[0054] The preparation method of the resin system is as follows:

[0055] Step S1, mix E44 epoxy resin, F-44 phenolic resin and bis(7-oxabicyclo[4.1.0]3-heptamethyl) adipate, heat to 60℃ and mix at a speed of 600 rpm for 16 min to obtain a composite resin matrix.

[0056] Step S2, mix isophorone diamine and phthalic anhydride, heat to 45℃ and mix at a speed of 500 rpm for 18 min to obtain a composite curing agent.

[0057] Step S3, mixing the polyether amine with the SiO2 / PMMA core-shell particles, heating to 150°C and mixing at a rotation speed of 1800 rpm for 12 min to obtain the composite toughening agent.

[0058] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and DMP-30, heating to 60°C and mixing for 30 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain the resin system.

[0059] Example 3

[0060] The resin system of the present example is prepared from the following raw materials:

[0061]

[0062] The preparation method of the resin system is as follows:

[0063] Step S1, mixing the E42 epoxy resin, the YDF-170 epoxy resin and the allyl glycidyl ether, heating to 75°C and mixing at a rotation speed of 1000 rpm for 20 min to obtain the composite resin matrix.

[0064] Step S2, mixing the diaminodiphenyl methane and the hexahydrophthalic anhydride, heating to 40°C and mixing at a rotation speed of 800 rpm for 15 min to obtain the composite curing agent.

[0065] Step S3, mixing the polyamide with the graphene, heating to 160°C and mixing at a rotation speed of 1500 rpm for 10 min to obtain the composite toughening agent.

[0066] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and DMP-30, heating to 100°C and mixing for 20 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain the resin system.

[0067] Example 4

[0068] The resin system of the present example is prepared from the following raw materials:

[0069]

[0070] The preparation method of the resin system is as follows:

[0071] Step S1, mixing the E51 epoxy resin, the F-51 phenolic resin and the bis(7-oxabicyclo[4.1.0]3-heptamethyl) adipate, heating to 80°C and mixing at a rotation speed of 400 rpm for 12 min to obtain the composite resin matrix.

[0072] Step S2, mixing 1,2-cyclohexanediamine and phthalic anhydride, heating to 80°C and mixing at a rotation speed of 650 rpm for 15 min to obtain a composite curing agent.

[0073] Step S3, mixing polyether block polymer L-61 and SiO2, heating to 80°C and mixing at a rotation speed of 1500 rpm for 20 min to obtain a composite toughening agent.

[0074] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and UR500, heating to 70°C and mixing for 22 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain a resin system.

[0075] Example 5

[0076] The resin system of the present example is prepared from the following raw materials:

[0077]

[0078] The preparation method of the resin system is as follows:

[0079] Step S1, mixing E44 epoxy resin and 3,4-epoxycyclohexylmethyl 3,4- epoxycyclohexylmethyl carboxylate, heating to 90°C and mixing at a rotation speed of 600 rpm for 18 min to obtain a composite resin matrix.

[0080] Step S2, mixing isophorone diamine and hexahydrophthalic anhydride, heating to 55°C and mixing at a rotation speed of 700 rpm for 17 min to obtain a composite curing agent.

[0081] Step S3, mixing polyamide and SiO2 / PU core-shell particles, heating to 130°C and mixing at a rotation speed of 1700 rpm for 18 min to obtain a composite toughening agent.

[0082] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and UR300, heating to 90°C and mixing for 21 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain a resin system.

[0083] Example 6

[0084] The resin system of the present example is prepared from the following raw materials:

[0085]

[0086] The preparation method of the resin system is as follows:

[0087] Step S1, mixing E42 epoxy resin and EHPE-3150 resin, heating to 60°C and mixing at a rotation speed of 200 rpm for 20 min to obtain a composite resin matrix.

[0088] Step S2, mixing diamino diphenyl sulfone and methyl nadic anhydride, heating to 80°C and mixing at a speed of 800 rpm for 15 min to obtain a composite curing agent.

[0089] Step S3, mixing polyether amine with SiO2 / PMMA core-shell particles, heating to 130°C and mixing at a speed of 1600 rpm for 10 min to obtain a composite toughening agent.

[0090] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and UR200, heating to 85°C and mixing for 27 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain a resin system.

[0091] Example 7

[0092] The resin system of the example was prepared from the following raw materials:

[0093]

[0094] The preparation method of the resin system was as follows:

[0095] Step S1, mixing E44 epoxy resin, YDF-161H epoxy resin and allyl glycidyl ether, heating to 65°C and mixing at a speed of 400 rpm for 18 min to obtain a composite resin matrix.

[0096] Step S2, mixing m-phenylenediamine and methyl nadic anhydride, heating to 45°C and mixing at a speed of 750 rpm for 20 min to obtain a composite curing agent.

[0097] Step S3, mixing polyamide with SiO2 / PMMA core-shell particles, heating to 140°C and mixing at a speed of 1700 rpm for 11 min to obtain a composite toughening agent.

[0098] Step S4, mixing the composite resin matrix, the composite curing agent, the composite toughening agent and BDMA, heating to 80°C and mixing for 26 min, then ultrasonic dispersion and vacuum defoaming treatment to obtain a resin system.

[0099] Comparative Example 1

[0100] The comparative example was prepared on the basis of Example 1 by removing the "composite toughening agent", and the preparation method was as described in Example 1 to obtain a resin system.

[0101] Comparative Example 2

[0102] The comparative example was prepared on the basis of Example 1 by removing the "nanoparticles", and the preparation method was as described in Example 1 to obtain a resin system.

[0103] Comparative Example 3

[0104] The comparative example was prepared on the basis of Example 1 by removing the "flexible polymer", and the preparation method was as described in Example 1 to obtain a resin system.

[0105] Comparative Example 4

[0106] The comparative example was prepared on the basis of Example 2 by adding 20 parts of polyether amine and 5 parts of SiO2 / PMMA core-shell particles, and the preparation method was as described in Example 2 to obtain a resin system.

[0107] Comparative Example 5

[0108] The comparative example was prepared on the basis of Example 2 by adding 5 parts of polyether amine and 40 parts of SiO2 / PMMA core-shell particles, and the preparation method was as described in Example 2 to obtain a resin system.

[0109] Comparative Example 6

[0110] The resin system of the comparative example was prepared from the following raw materials:

[0111]

[0112] The preparation method was as described in Example 1 to obtain a resin system.

[0113] Comparative Example 7

[0114] The resin system of the comparative example was prepared from the following raw materials:

[0115]

[0116] The preparation method was as described in Example 4 to obtain a resin system.

[0117] Comparative Example 8

[0118] The resin system of the comparative example was prepared from the following raw materials:

[0119]

[0120] The preparation method of the resin system was as follows:

[0121] Step S1, the E51 epoxy resin was heated to 90°C, stirred at 1000 rpm for 20 min, then vacuum degassing treatment for 30 min, and cooled to 50°C to obtain component A.

[0122] Step S2, methyl nadic anhydride, phenyl glycidyl ether, DPM-30 and polyethylene glycol were mixed, stirred at 700 rpm for 20 min, then vacuum degassing treatment for 30 min to obtain component B.

[0123] Step S3, the A component and the B component are mixed according to a weight ratio of 1:1 to obtain a prepolymer, which is cast in a mold and cured by temperature rising; the temperature rising curing conditions are: 150℃ / 2h+180℃ / 4h+200℃ / 4h+230℃ / 2h, after curing, the mold is cooled to room temperature in the oven, demolded to obtain the resin system.

[0124] The process performance of the resin systems prepared in Examples 1-7 above was evaluated, and the test referred to the standard method, and the performance statistics of the above resin systems are shown in Table 1:

[0125] Table 1 Evaluation results of process performance of resin systems

[0126]

[0127] From Table 1, it can be seen that the gel time of Examples 1-7 is between 25 and 30 minutes, which shows that the resin system can quickly start curing at 120℃, but has not yet completely cured. This rapid gelation property enables the resin system to quickly form a certain shape during processing while maintaining a certain fluidity, avoiding the difficulty of premature curing.

[0128] The glass transition temperature Tg of Examples 1-7 is between 142℃ and 155℃, which shows that the resin system has high thermal stability. High Tg value means that the material can still maintain good mechanical properties at high temperature, which is particularly important for the application of low-temperature high-pressure hydrogen storage cylinders. In this application scenario, the material needs to ensure that its performance is not affected at high temperature. In the heating process of the preparation process, there are two main purposes: on the one hand, heating can increase the kinetic energy of gas molecules, making them more easily diffuse out of the resin matrix. This process is necessary to remove residual gases and volatile organic compounds in the hydrogen storage cylinder to ensure the sealing performance of the gas cylinder and the purity of the gas. On the other hand, as the temperature decreases, the movement of gas molecules slows down, and the vacuum degree will further improve. During the heating process, inert gas (such as nitrogen) is usually introduced for gas replacement, which aims to: expel air and water remaining in the pores of the material, which may affect the performance of the hydrogen storage cylinder and the purity of hydrogen.

[0129] The viscosity of Examples 1-7 at 30℃ is between 46.3 and 57.2 Pa·s, which shows that the resin system has high viscosity at room temperature. This high viscosity enables the resin system to maintain good tackiness at room temperature, but not too dry.

[0130] The viscosity of the resin systems of Examples 1-7 at 100°C is between 0.12 and 0.23 Pa·s, showing that the resin systems have good flowability at high temperature. This moderate high-temperature viscosity ensures that the resin systems can be uniformly distributed during the curing process while maintaining a certain stickiness.

[0131] In summary, the resin systems of the embodiments of the present application exhibit good balance in key process performance indicators such as gel time, curing time, glass transition temperature, and viscosity. The comprehensive optimization of these properties enables the resin systems to quickly form a certain shape during processing while maintaining appropriate stickiness, avoiding premature curing or excessive dryness. This "sticky but not dry" characteristic not only improves the convenience of operation, but also ensures that the resin systems can be uniformly distributed during the curing process, forming high-quality composite materials. Therefore, the resin systems of the embodiments of the present application can effectively meet the preparation needs of high-performance composite materials such as low-temperature high-pressure hydrogen storage cylinders.

[0132] The mechanical properties of the resin systems prepared in Examples 1-7 and Comparative Examples 1-7 above were evaluated, and the tests were performed in accordance with standard methods. The performance statistics of the above resin systems are shown in Table 2:

[0133] Table 2: Mechanical property evaluation results of resin systems

[0134]

[0135] As can be seen from Table 2, comparing Examples 1 and Comparative Examples 1-3, the tensile strength, elongation at break, and fracture toughness of Example 1 at room temperature are significantly higher than those of Comparative Examples 1-3, indicating that it has higher strength and toughness at room temperature. The tensile strength, elongation at break, and fracture toughness of Example 1 at 90K are also significantly higher than those of Comparative Examples 1-3, indicating that it can still maintain high strength and toughness at low temperature. This is because the composite toughening agent (such as polyether block polymer L-61 and SiO2 / PU core-shell particles) is added in Example 1, which can effectively absorb impact energy and delay crack propagation at low temperature, thereby significantly improving the low-temperature toughness and fracture toughness of the resin system. Nanoparticles (such as SiO2 / PU core-shell particles) deflect or passivate cracks, avoiding crack propagation, further enhancing the crack resistance of the resin system. In Comparative Example 1, the composite toughening agent is removed, in Comparative Example 2, the nanoparticles are removed, and in Comparative Example 3, the flexible polymer is removed, which leads to a significant decrease in the performance of the resin system at low temperature.

[0136] Compared with Comparative Examples 4-5, Example 2 has significantly higher tensile strength, elongation at break and fracture toughness at room temperature, indicating that it has higher strength and toughness at room temperature. Example 2 also has significantly higher tensile strength, elongation at break and fracture toughness at 90K than Comparative Examples 4-5, indicating that it can still maintain high strength and toughness in a low-temperature environment. This is because the ratio of flexible polymer and nanoparticles in Comparative Example 4 is not properly adjusted, and an excessive amount of composite toughening agent can cause the performance of the resin system to decrease, especially in terms of tensile strength. The SiO2 / PMMA core-shell particles in Comparative Example 5 have a relatively high specific surface area and surface energy. When the amount is too high, it can significantly increase the viscosity of the resin system. This is because the nanoparticles form a network structure when dispersed in the resin, limiting the flow of resin molecules. It also causes the interaction between SiO2 / PMMA core-shell particles to increase, making it easy to agglomerate. Agglomerated SiO2 / PMMA core-shell particles form larger particles that are difficult to disperse uniformly in the resin, and the agglomerated SiO2 / PMMA core-shell particles form stress concentration points, reducing the toughness and strength of the resin system.

[0137] Compared with Comparative Example 6, Example 1 has significantly higher tensile strength, elongation at break and fracture toughness at room temperature, indicating that it has higher strength and toughness at room temperature. Example 1 also has significantly higher tensile strength, elongation at break and fracture toughness at 90K than Comparative Example 6, indicating that it can still maintain high strength and toughness in a low-temperature environment. This is because Comparative Example 6 uses tetra(2-hydroxyethyl) hexanediamide, tetramethylammonium hydroxide and polyetheramine components. Although tetra(2-hydroxyethyl) hexanediamide and polyetheramine can react with epoxy groups, the introduction of polyetheramine can reduce the density of the cross-linked network formed by the system, thereby weakening the mechanical strength and fracture toughness of the material. In addition, Comparative Example 6 only adds a high proportion of polyetheramine to improve toughness, which can cause too many flexible segments to reduce the cross-linking strength of the material, thereby causing the Tg of the material to decrease, affecting the performance of the material at high temperatures.

[0138] A comparison of Example 4 and Comparative Example 7 shows that Example 4 exhibits significantly higher tensile strength, elongation at break, and fracture toughness at room temperature than Comparative Example 7, indicating higher strength and toughness at room temperature. Example 4 also demonstrates significantly higher tensile strength, elongation at break, and fracture toughness at 90K than Comparative Example 7, indicating that it maintains high strength and toughness even at low temperatures. This is because Comparative Example 7 used different formulations (such as YD128, dicyandiamide, UR500, and polyetheramine). While the combination of YD128 and dicyandiamide provides a higher crosslinking density, neither the resin nor the curing agent is a composite system, only exhibiting the individual properties of one resin and curing agent, lacking a synergistic effect between systems. Furthermore, the high proportion of polyetheramine in the system, while contributing to improved material toughness, weakens the resin strength, thus failing to meet the synergistic requirements of low-temperature, high-pressure vessels for comprehensive performance such as strength, toughness, and heat resistance.

[0139] Please see Figure 1 , Figure 1 The temperature-viscosity curves are for the resin systems prepared in Example 1 and Comparative Example 8. From... Figure 1 Figure (a) shows the temperature-viscosity curve of the resin system in Example 1. It can be seen that at 25°C, the viscosity of the dry resin system in Example 1 is as high as 72308 mPa·s, indicating that the resin system has high molecular chain entanglement density and structural integrity at room temperature. As the temperature increases, the viscosity decreases significantly, dropping to 477 mPa·s at 100°C. This indicates that the dry resin system has good fluidity during heating, which is beneficial for impregnation and distribution during the winding process. The high viscosity characteristic helps to enhance the resin's coating of fibers, thereby improving the mechanical properties and dimensional stability of the composite material. At the same time, it reduces the problems of uneven resin distribution and environmental pollution caused by excessive flow, making it suitable for the efficient preparation of high-performance composite materials.

[0140] from Figure 1 Figure (b) shows the temperature-viscosity curve of the resin system in Comparative Example 8. It can be seen that at 25°C, the viscosity of the wet-process resin system in Comparative Example 8 is 982 mPa·s, significantly lower than that of the dry-process resin system in Example 1, indicating that its molecular chain entanglement density and structural integrity are relatively low. Similarly, the viscosity decreases significantly with increasing temperature, dropping to 102 mPa·s at 100°C. The wet-process resin system of Comparative Example 8 also exhibits good fluidity during heating. Although the viscosity is low, the wet-process resin system of Comparative Example 8 may require more control during the winding process to ensure uniform resin distribution and impregnation.

[0141] Therefore, the dry resin system provided by the embodiments of the present application can exhibit excellent processing characteristics in the winding forming process. The resin system exhibits the characteristics of "sticky but not sticky" at 25°C, which means that the resin system maintains a certain stickiness while not generating excessive adhesion, so that the resin system can maintain good operability and forming stability under the condition of high-speed winding (speed of 100 to 200 meters / minute). In addition, the resin system can be cross-linked and cured to form a final product after a short curing process of heating at 100°C for 1 hour, heating at 120°C for 1 hour, and heating at 130°C for 1 hour. This process is not only efficient and low in energy consumption, but also very suitable for large-scale production applications, showing its significant advantages in industrial production.

[0142] It should also be noted that the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or further include elements inherent in such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0143] The above only describes the embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

[0144] Although the embodiments of the present application are described in conjunction with the drawings, those skilled in the art can make various modifications and changes without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A resin system, characterized in that, The resin system comprises the following components in parts by weight: 100 parts of composite resin matrix, 25-60 parts of composite curing agent, 1-2 parts of accelerator, and 2-20 parts of composite toughening agent. The composite resin matrix is ​​obtained by mixing resin A and resin B in a weight ratio of 70-90:10-30. The resin A is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and liquid phenolic resin; wherein, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, and E42 epoxy resin; the bisphenol F epoxy resin is selected from at least one of YDF-161H epoxy resin and YDF-170 epoxy resin; and the liquid phenolic resin is selected from at least one of F-51 phenolic resin and F-44 phenolic resin. The resin B is selected from at least one of alicyclic epoxy resins and flexible side-chain epoxy resins; wherein the alicyclic epoxy resin is selected from at least one of EHPE-3150 resin, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarbamate; and the flexible side-chain epoxy resin is allyl glycidyl ether. The composite curing agent is obtained by mixing curing agent A and curing agent B in a weight ratio of 5-30:12-40; The curing agent A is a latent amine curing agent; wherein, the latent amine curing agent is selected from at least one of dicyandiamide, isophorone diamine, 1,2-cyclohexanediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, and m-phenylenediamine; The curing agent B is an acid anhydride curing agent; wherein, the acid anhydride curing agent is selected from at least one of methylnadic anhydride, phthalic anhydride, and hexahydrophthalic anhydride; The composite toughening agent is obtained by mixing a flexible polymer and nanoparticles in a weight ratio of 1-20:1-10; the flexible polymer is selected from at least one of polyether block polymer L-61, polyetheramine, and polyamide, and the molecular weight of the flexible polymer is greater than 1500; the nanoparticles are selected from at least one of silica, graphene, SiO2 / PU core-shell particles, and SiO2 / PMMA core-shell particles.

2. The resin system according to claim 1, characterized in that, The accelerator is selected from at least one of organic urea accelerators, tertiary amine accelerators, and boramine complexes; wherein... The organic urea accelerator is selected from at least one of UR200, UR300, and UR500; The tertiary amine accelerator is selected from at least one of DMP-30 and BDMA.

3. A method for preparing the resin system according to any one of claims 1-2, characterized in that, The method for preparing the resin system includes: Mix resin A and resin B, heat to 60-100℃ and mix at 200-1000 rpm for 10-20 minutes to obtain a composite resin matrix; Mix curing agent A and curing agent B, heat to 40-80℃ and mix at 500-800 rpm for 15-20 minutes to obtain a composite curing agent; The flexible polymer and nanoparticles are mixed, heated to 80-160℃ and mixed at 1500-2000 rpm for 10-20 minutes to obtain a composite toughening agent. The composite resin matrix, the composite curing agent, the composite toughening agent and the accelerator are mixed, heated to 60-100℃ and mixed for 20-30 minutes, then ultrasonically dispersed and vacuum defoamed to obtain the resin system.

4. A method for preparing prepreg yarn, characterized in that, The method for preparing the prepreg yarn includes: After adding the resin system to the impregnation tank and heating it to 50°C, the heated resin system is evenly spread on the release paper and fully impregnated with the reinforcing fibers to obtain prepreg yarn; wherein, the resin system is the resin system according to any one of claims 1-2 or the resin system prepared by the resin system preparation method according to claim 3. Release paper is laid flat on the surface of the prepreg filament, the prepreg filament is pre-cured, and then cooled. After cooling, the release paper is peeled off, a polyethylene film is laid on the surface, and the filament is wound up to obtain the prepreg filament.

5. The method for preparing prepreg yarn according to claim 4, characterized in that, The pre-curing temperature is 120℃, the heating time is 20-30 minutes, and the prepreg obtained by winding is placed at room temperature for at least 60 days.

6. An application of a prepreg yarn, characterized in that, The prepreg filaments prepared by the method of any one of claims 4-5 are used in low-temperature high-pressure hydrogen storage cylinders.

7. The application according to claim 6, characterized in that, The prepreg filaments are heated and cured, then cooled to obtain a low-temperature, high-pressure hydrogen storage cylinder. The curing conditions are: 100℃ / 1h + 120℃ / 1h + 130℃ / 1h.

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