Composite material for cylindrical shell and preparation method thereof

Abstract

The invention belongs to the technical field of fiber composite materials, and particularly relates to a composite material for a cylindrical shell and a preparation method thereof.The composite material for the cylindrical shell is prepared from, by weight, 100 parts of composite modified epoxy resin, 12-25 parts of composite modified MBS flexibilizer, 25-35 parts of curing agent, 0.5-2 parts of accelerant, 0.5-1.5 parts of ultraviolet light absorber and 0.3-0.8 part of antioxidant. 1-3 parts of a thixotropic agent and 180-220 parts of glass fiber; according to the composite material for the cylindrical shell, the composite modified epoxy resin and the composite modified MBS toughening agent are introduced, and a specific forming process is combined, so that the composite material finally meets the basic requirements of high strength and high modulus of a structural part, and meanwhile, the composite material also has good toughness, environmental aging resistance, mechanical property and interface bonding strength; the comprehensive performance is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of fiber composite materials technology, and specifically to a composite material for cylindrical shells and its preparation method. Background Technology

[0002] Fiber-reinforced resin matrix composites are widely used in aerospace, transportation, wind power generation, and high-pressure vessels due to their advantages such as high specific strength, high specific modulus, excellent fatigue resistance, and strong designability. Among them, composites with epoxy resin as the matrix and glass fiber as the reinforcing phase occupy an important position in the manufacture of load-bearing structural components such as cylindrical shells due to their good comprehensive performance and relatively low cost. Traditional epoxy resin matrix composites still face the following technical bottlenecks in practical applications: First, after curing, epoxy resin forms a highly cross-linked three-dimensional network structure, resulting in inherent brittleness, insufficient impact resistance, and insufficient fracture toughness. When a cylindrical shell made of composite material is subjected to impact loads or dynamic stress, it is prone to brittle fracture under low stress, generating cracks that propagate rapidly, seriously threatening the safety and service life of the structure. To solve this problem, toughening methods are usually adopted by adding rubber elastomers such as carboxyl-terminated nitrile rubber or thermoplastic resins. However, simple physical blending toughening agents often come at the cost of significantly sacrificing the material's strength, modulus, and heat resistance, making it difficult to achieve a good balance between high strength and high toughness.

[0003] Secondly, glass fiber reinforced epoxy composites are quite sensitive to humid and hot environments. Under high temperature and high humidity, moisture penetrates along the fiber / resin interface, leading to a decrease in interfacial bond strength, a "plasticizing" effect, a reduction in the glass transition temperature, and a significant degradation in mechanical properties. While traditional methods may add additives such as UV absorbers and antioxidants, it is difficult to fundamentally improve the long-term environmental aging resistance of the material at the molecular structure and interfacial chemistry level of the resin matrix.

[0004] Therefore, developing a new type of composite material for cylindrical shells that can fundamentally and significantly improve the toughness, impact resistance, resistance to damp heat aging, and process adaptability of epoxy resin-based composite materials while maintaining their high strength and high modulus properties has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the problems of the existing technologies, this invention provides a composite material for cylindrical shells and its preparation method. The composite material for cylindrical shells provided by this invention introduces a composite modified epoxy resin and a composite modified MBS toughening agent, combined with a specific molding process, ultimately enabling the composite material to meet the basic requirements of high strength and high modulus for structural components, while also possessing good toughness, environmental aging resistance, mechanical properties, and interfacial bonding strength, resulting in a significant improvement in overall performance.

[0006] The technical solution of the present invention to solve the above problems is as follows:

[0007] A composite material for cylindrical shells comprises the following components by weight: 100 parts of composite modified epoxy resin, 12-25 parts of composite modified MBS toughening agent, 25-35 parts of curing agent, 0.5-2 parts of accelerator, 0.5-1.5 parts of ultraviolet absorber, 0.3-0.8 parts of antioxidant, 1-3 parts of thixotropic agent, and 180-220 parts of glass fiber.

[0008] The preparation method of the composite modified epoxy resin includes the following steps:

[0009] Step 1: Add carboxyl-terminated butadiene-acrylonitrile rubber and liquid polysulfide rubber to bisphenol A type epoxy resin at 115-125℃, stirring speed 200-250rpm, and under a nitrogen atmosphere, and react for 1.5-2.5 hours.

[0010] Step 2: Bisphenol F epoxy resin and silane coupling agent are added sequentially to the resin after the reaction in Step 1. The mixture is heated to 73-78°C under a nitrogen atmosphere and reacted for 2-3 hours to obtain silane-modified resin.

[0011] Step 3: Heat the silane-modified resin obtained in Step 2 to 78-82℃, add hydrophobic fumed silica and titanate coupling agent in sequence, and perform shear degassing treatment.

[0012] Step 4: Mix methyl methacrylate, butyl acrylate, and benzoyl peroxide evenly to obtain mixture A. Mix methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile evenly to obtain mixture B. Add polymerization inhibitor, solution A, and solution B to the resin obtained in step 3 and react to obtain acrylate grafted resin.

[0013] Step 5: Add organosilicon leveling agent, part of isophorone diisocyanate and catalyst to the acrylate grafted resin obtained in Step 4, and react at 72-78℃ for 30-40 minutes under a nitrogen atmosphere. Add the remaining isophorone diisocyanate, 1,4-butanediol, diethylene glycol and triethyl phosphate, and continue to react at 75-80℃ for 70-100 minutes to obtain the final product.

[0014] Preferably, in step 1, the mass ratio of the bisphenol A type epoxy resin, the carboxyl-terminated nitrile rubber, and the liquid polysulfide rubber is 100:8-12:1-3; in step 2, the mass ratio of the resin after the reaction in step 1, the bisphenol F type epoxy resin, and the silane coupling agent is 100:35-40:4-6.

[0015] Preferably, in step 3, the mass ratio of the silane-modified resin, fumed silica, and titanate coupling agent is 100:6-10:1.5-2.5.

[0016] Preferably, in step 4, the mass ratio of methyl methacrylate, butyl acrylate, and benzoyl peroxide in mixture A is 9-11:5-6.5:0.075-0.1, and the mass ratio of methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile in mixture B is 9-11:5-6.5:0.075-0.1:0.02-0.03. The mass ratio of the resin obtained after degassing in step 3, the polymerization inhibitor, methyl methacrylate in mixture A, and methyl methacrylate in mixture B is 100:0.08-0.12:9-11:9-11.

[0017] Preferably, in step 5, the mass ratio of the acrylate grafted resin, the silicone leveling agent, the total amount of isophorone diisocyanate, the catalyst, 1,4-butanediol, diethylene glycol, and triethyl phosphate is 100:0.5-1.0:9-13:0.06-0.09:3-5:1.0-2.0:0.4-0.7.

[0018] Preferably, the preparation method of the composite modified MBS toughening agent includes the following steps:

[0019] Step a: First, pretreat the MBS powder. Add the pretreated MBS powder to a mixed solvent, adjust the pH to 5.2-5.5, heat to 72-76℃, add silane coupling agent KH-570 at 300-400 rpm, react for 2-2.5 hours, cool to 45-55℃, adjust the pH to 6.5-7.0, purify, and obtain modified material 1.

[0020] Step b: Add modified material 1 to toluene, add glycidyl methacrylate and the polymerization inhibitor hydroquinone at 200-250 rpm, heat to 72-78℃, add benzoyl peroxide under nitrogen atmosphere, react for 2.2-2.7 hours, purify to obtain modified material 2;

[0021] Step c: Disperse modified material 2 in deionized water, add emulsifier sodium dodecyl sulfate, heat to 72-76℃ and rotate at 400-500 rpm, add butyl acrylate, methyl methacrylate, crosslinking agent ethylene glycol dimethacrylate and potassium persulfate aqueous solution, react for 2-2.5 hours, add tert-butyl hydrogen peroxide, keep at 68-72℃ for 35-45 minutes, cool to 40-50℃, add composite coagulant solution under stirring to coagulate, and purify to obtain the final product.

[0022] Preferably, in step a, the mass ratio of the pretreated MBS powder, silane coupling agent KH-570, and mixed solvent is 100:4-6:50-75, and the mass ratio of anhydrous ethanol and water in the mixed solvent is 50-80:1-2.

[0023] Preferably, in step b, the mass ratio of the modified material 1, toluene, glycidyl methacrylate, polymerization inhibitor hydroquinone, and benzoyl peroxide is 100:200-250:6-8:0.05-0.08:0.12-0.18.

[0024] Preferably, in step c, the mass ratio of the modified material 2, deionized water, emulsifier sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, potassium persulfate, and tert-butyl hydroperoxide is 100:300-400:1.5-2.2:18-22:12-16:0.3-0.6:0.25-0.35:0.15-0.25; the mass ratio of potassium persulfate to deionized water in the potassium persulfate aqueous solution is 0.25-0.35:10-15; and the concentration of calcium chloride in the composite coagulant solution is 2-4‰, and the concentration of sodium sulfate is 12-18‰.

[0025] The preparation method of the above-mentioned composite material for cylindrical shells specifically includes:

[0026] The first step involves mixing the composite modified epoxy resin, composite modified MBS toughening agent, ultraviolet absorber, antioxidant, thixotropic agent, solvent, curing agent, and accelerator to obtain a resin solution.

[0027] The second step involves controlling the glass fiber tension to 0.5-1.0N per bundle of yarn, setting the glue bath temperature to 45-50℃, placing the resin solution into the glue bath, and allowing the glass fiber to pass through the glue bath at a speed of 0.8-1.2m / min for a immersion time of ≥30 seconds to obtain the prepreg.

[0028] The third step is to place the prepreg into the mold and heat-press it for curing.

[0029] The fourth step is to perform post-curing treatment after demolding to obtain the final product.

[0030] The present invention has the following beneficial effects:

[0031] The composite material for cylindrical shells provided by this invention, through the introduction of composite modified epoxy resin and composite modified MBS toughening agent, combined with a specific molding process, ultimately achieves a significant improvement in comprehensive performance while meeting the basic requirements of high strength and high modulus for structural components. It exhibits particularly excellent performance in toughness, environmental aging resistance, process adaptability, and interfacial bonding strength. This composite material, reinforced with high-content glass fiber and combined with a high-performance resin matrix, endows the material with high strength, high modulus, and excellent dimensional stability, meeting the mechanical requirements of cylindrical shells as load-bearing structural components. Through the synergistic toughening mechanism of the composite modified MBS toughening agent and the matrix resin, the material maintains high strength while significantly improving impact resistance and fracture toughness, overcoming the drawback of high brittleness in traditional glass fiber reinforced epoxy resins. The components incorporate ultraviolet absorbers and antioxidants, and particularly through molecular structure modification of the resin and toughening agent, effectively enhance the composite material's resistance to environmental factors such as ultraviolet radiation, humidity, and oxidation, extending its service life. The thixotropic agents and specific rheological modifications in the resin system ensure suitable wettability and viscosity stability of the adhesive during glass fiber impregnation, preventing sagging and ensuring the uniformity of the prepreg quality. Precisely controlled impregnation and curing processes guarantee low porosity and high quality in the final product.

[0032] Among them, the composite modified epoxy resin organically introduces a variety of functional components into the epoxy resin molecular structure, achieving a comprehensive improvement in its performance. In step 1, carboxyl-terminated nitrile rubber and liquid polysulfide rubber are respectively incorporated into the bisphenol A type epoxy backbone through carboxyl-epoxy and mercapto-epoxy ring-opening reactions, forming a flexible chain segment suspension structure, which effectively reduces the crosslinking density of the epoxy resin, increases the flexibility of the molecular chain, and improves the elongation at break. In step 2, the addition of bisphenol F type epoxy resin reduces the viscosity of the system, improves processing fluidity, and increases the wetting rate of fibers. At the same time, its low aromatic density structure increases the flexibility of the chain segments between crosslinking points, providing active sites for subsequent acrylate grafting. The silane coupling agent generates a covalently bonded siloxane layer on the glass fiber surface, improving the interfacial shear strength. In step 3, hydrophobic fumed silica forms a three-dimensional network structure under the action of titanate coupling agent, which increases the thixotropic index of the resin solution and can effectively prevent the resin from sagging during vertical construction or storage. In step 4, hydroxyl-containing acrylate side chains are introduced onto the epoxy backbone via free radical polymerization, increasing the hydroxyl value and providing a sufficient active hydrogen source for the isocyanate reaction in step 5. In step 5, isophorone diisocyanate first reacts with the hydroxyl groups of the acrylate side chains to generate an isocyanate-terminated prepolymer, which is then extended with 1,4-butanediol and diethylene glycol to form urethane bonds. The resulting epoxy-acrylate-polyurethane hybrid resin maintains a high glass transition temperature while retaining good flexibility at low temperatures, indicating that its hard and soft segment structure effectively balances heat resistance and cold resistance. The addition of silicone leveling agents significantly improves the leveling properties of the adhesive and reduces the surface roughness of the cured product, meeting the requirements for aerodynamic surface smoothness in applications such as wind turbine blades. Triethyl phosphate promotes resin charring at high temperatures, allowing for faster formation of a continuous char layer on the resin surface, blocking heat and oxygen transfer to the interior, thereby reducing the combustion rate and inhibiting flame spread.

[0033] In the aforementioned composite modified MBS toughening agent, in step a, the alkoxy groups of the silane coupling agent condense with the polar groups on the MBS surface after hydrolysis, and the unsaturated double bonds at the other end are pre-introduced onto the MBS surface, providing polymerizable sites for subsequent grafting of glycidyl methacrylate; simultaneously, the silane layer reduces the surface energy of the particles, significantly reducing agglomeration. In step b, the double bonds on the MBS surface undergo free radical grafting with glycidyl methacrylate, and the epoxy groups of glycidyl methacrylate can undergo ring-opening reactions with the hydroxyl groups or active hydrogen in the resin matrix during the curing stage to form covalent bonds, thereby improving the interfacial shear strength. Step c involves coating MBS grafted with glycidyl methacrylate using emulsion polymerization to form a shell of butyl acrylate-methyl methacrylate random copolymer. Butyl acrylate provides soft segments with low glass transition temperatures, while methyl methacrylate provides high surface hardness and solubility parameters that match the epoxy group, keeping the shell in a highly elastic state at the curing temperature. The crosslinking agent ethylene glycol dimethacrylate introduces crosslinking points into the shell copolymer, ensuring that the shell maintains structural integrity and does not break or dissolve under subsequent solvent, shear, and curing temperatures. The crosslinked shell allows the toughening particles to maintain a complete spherical shape and nanoscale dispersion throughout resin mixing, high-temperature curing, and long-term service, thereby continuously inhibiting craze propagation and energy dissipation. The impact toughness no longer decreases due to particle breakage or agglomeration, thus significantly improving the material's impact resistance and fracture toughness.

[0034] In the composite material of this invention, the composite modified epoxy resin achieves a good toughness foundation through the rubber segments introduced in step 1 and the polyurethane blocks formed in step 5. The addition of the composite modified MBS toughening agent provides a second, more efficient toughening mechanism. The core-shell structure of MBS particles can induce more and denser crazes and shear bands in the matrix, consuming a large amount of impact energy. At the same time, the epoxy resin matrix itself has been modified to be more flexible, which provides a more favorable microenvironment for the deformation of MBS particles and the initiation and expansion of crazes, avoiding the situation where MBS particles cannot function effectively due to an overly hard matrix. The two complement each other, greatly improving the impact resistance and fracture toughness of the material, far exceeding the effect of single toughening or matrix modification. The silane coupling agent modification in step 2 significantly improves the interfacial adhesion between the composite modified epoxy resin and reinforcing materials such as glass fiber. The composite modified MBS toughening agent, grafted with glycidyl methacrylate in step b, also possesses functional groups capable of reacting with epoxy resin, exhibiting excellent compatibility and interfacial adhesion with the epoxy resin matrix. Therefore, throughout the composite material, strong and tough interfaces are formed between the reinforcing fibers and the matrix, as well as between the toughening agent and the matrix. This facilitates the uniform distribution and effective transfer of stress within the material, preventing early failure due to weak local interfaces, thereby improving the overall load-bearing capacity and durability of the material. Simultaneously, the composite modified epoxy resin provides excellent weather resistance, chemical corrosion resistance, and mechanical strength, while the composite modified MBS toughening agent, while ensuring good compatibility with the matrix, primarily addresses the material's brittleness, significantly improving toughness and impact resistance. The combination of these two elements results in a final cylindrical shell composite material that not only possesses high strength and high modulus to meet structural load-bearing requirements but also exhibits excellent toughness, along with good weather resistance and durability to adapt to various complex environments. Attached Figure Description

[0035] Figure 1 The graph shows the test results of tensile strength and compressive strength of the composite materials obtained in Examples 1-3 and Comparative Examples 1-3;

[0036] Figure 2 The graph shows the impact strength test results of the composite materials obtained in Examples 1-3 and Comparative Examples 1-3. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] All of the following raw materials are commercially available.

[0039] UV absorber, UV-531, Hebei Kuoyou Chemical Technology Co., Ltd.; Antioxidant 1010, Nanjing Milan Chemical Co., Ltd.; Fumed silica, hydrophobic, 99.8% purity, model: EROSILR202, brand: Degussa, purchased from Guangzhou Jingyi New Materials Co., Ltd.; Bisphenol A epoxy resin, CAS No. 25085-99-8, brand: Jixin Yibang; Carboxyl-terminated nitrile butadiene rubber (CTBN), CAS No. 25265-19-4, brand: Chengfeng; Liquid polysulfide rubber, grade JLY-121, purity 99%, Hubei Kewode Chemical Co., Ltd.; Bisphenol F type epoxy resin, epoxy equivalent (g / eq) 160~180, brand: Huiya New Materials; Titanate coupling agent, effective ingredient content 99%, Nanjing Xuanhao New Materials Technology Co., Ltd.; Organosilicon leveling agent, BYK-310, purity 99%, Hubei Watson Chemical Technology Co., Ltd.; MBS powder, Kanekachi M722, Suzhou Zhongzesheng New Materials Co., Ltd.; Glass fiber is untwisted roving alkali-free glass fiber, compressive strength 1800MPa, density 2.6kg / m³, appearance: filament, Taian Songze Composite Materials Co., Ltd.

[0040] Example 1

[0041] A composite material for cylindrical shells comprises the following components by weight: 100 parts of composite modified epoxy resin, 18 parts of composite modified MBS toughening agent, 30 parts of curing agent, 1.2 parts of accelerator, 1 part of ultraviolet absorber, 0.5 parts of antioxidant, 2 parts of thixotropic agent, and 200 parts of alkali-free glass fiber roving; wherein the curing agent is methyltetrahydrophthalic anhydride, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, the ultraviolet absorber is UV-531, the antioxidant is antioxidant 1010, and the thixotropic agent is fumed silica;

[0042] The preparation method of the composite modified epoxy resin includes the following steps:

[0043] Step 1: At 120°C, with a stirring speed of 220 rpm, and under a nitrogen atmosphere, carboxyl-terminated nitrile butadiene rubber and liquid polysulfide rubber are added to bisphenol A type epoxy resin and reacted for 2 hours; wherein, the mass ratio of bisphenol A type epoxy resin, carboxyl-terminated nitrile butadiene rubber, and liquid polysulfide rubber is 100:10:2.

[0044] Step 2: Cool the resin after the reaction in Step 1 to 65°C, add bisphenol F epoxy resin and silane coupling agent KH-550 sequentially at 180 rpm, heat to 75°C under a nitrogen atmosphere, and react for 2.5 hours to obtain silane-modified resin; wherein, the mass ratio of the resin after the reaction in Step 1, bisphenol F epoxy resin, and silane coupling agent is 100:38:5;

[0045] Step 3: The silane-modified resin obtained in Step 2 is heated to 80°C, and hydrophobic fumed silica and titanate coupling agent are added sequentially. The mixture is sheared at 3800 rpm for 12 minutes, during which cooling water is circulated to maintain the reactor temperature ≤80°C. The temperature is then raised to 85°C, and shearing is continued at 4200 rpm for 35 minutes. After shearing, the mixture is degassed for 35 minutes under a vacuum of ≤200 mbar and a temperature of 60°C. The mass ratio of the silane-modified resin, fumed silica, and titanate coupling agent is 100:8:2.

[0046] Step 4: Mix methyl methacrylate, butyl acrylate, and benzoyl peroxide evenly to obtain mixture A. Mix methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile evenly to obtain mixture B. Add the polymerization inhibitor p-hydroxyanisole to the resin obtained after degassing in Step 3 at 70℃ and 550 rpm, and stir for 10 minutes. Then, under nitrogen protection, add solution A dropwise at a rate of 22 mL / min. After the addition is complete, react for 80 minutes, then add solution B dropwise at a rate of 18 mL / min. The reaction was continued for 1.8 hours to obtain acrylate grafted resin; wherein, in mixture A, the mass ratio of methyl methacrylate, butyl acrylate, and benzoyl peroxide was 10:5.8:0.9, and in mixture B, the mass ratio of methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile was 10:5.8:0.9:0.025; and the mass ratio of the resin obtained after degassing in step 3, the polymerization inhibitor p-hydroxyanisole, the methyl methacrylate in mixture A, and the methyl methacrylate in mixture B was 100:0.1:10:10.

[0047] Step 5: Cool the acrylate grafted resin obtained in Step 4 to 65°C, and add the silicone leveling agent, isophorone diisocyanate (68% of the total isophorone diisocyanate content), and catalyst dibutyltin dilaurate sequentially at 320 rpm. React at 75°C for 35 minutes under nitrogen protection. Add the remaining isophorone diisocyanate, 1,4-butanediol, diethylene glycol, and triethyl phosphate, and continue the reaction at 78°C for 85 minutes. Then, at 78°C and a vacuum degree ≤5mb, the reaction is completed. Triethyl phosphate and other volatiles were removed under AR conditions for 35 minutes. After filtration through a 5μm filter bag, the mixture was aged at 50±2℃ and a vacuum of 0.09MPa for 2.2 hours to obtain the final product. The mass ratio of the acrylate grafted resin, silicone leveling agent, total isophorone diisocyanate, dibutyltin dilaurate, 1,4-butanediol, diethylene glycol, and triethyl phosphate was 100:0.8:11:0.08:4:1.5:0.5.

[0048] The preparation method of the composite modified MBS toughening agent includes the following steps:

[0049] Step a: First, pretreat the MBS powder as follows: Add the MBS powder to anhydrous ethanol and ultrasonically disperse it at 45°C for 40 minutes under conditions of 700W power and 40kHz frequency. Centrifuge the dispersion at 4000rpm for 7 minutes, collect the supernatant, filter it through a 200-mesh sieve, centrifuge the filtrate again, and dry the resulting solid at 50°C and a vacuum degree ≤100mbar for 2.2 hours. Add the pretreated MBS powder to a mixed solvent, adjust the pH to 5.2-5.5 with 0.1% acetic acid, heat to 75°C, and at 350rpm, pre-dissolve the silane coupling agent KH-570 in anhydrous ethanol, then slowly add it dropwise to the MBS powder at a rate of 26mL / min. After the addition of the mixture to the final mixture is complete, the reaction is carried out for 2.2 hours, cooled to 50°C, neutralized with triethylamine to a pH of 6.5-7.0, centrifuged at 4000 rpm for 7 minutes, the supernatant is discarded, washed twice with anhydrous ethanol, and dried at 50°C for 1.8 hours to obtain modified material 1; wherein, in the MBS powder pretreatment process, the mass ratio of MBS powder to anhydrous ethanol is 100:300-450, the mass ratio of the pretreated MBS powder, silane coupling agent KH-570, and mixed solvent is 100:5:60, in the mixed solvent, the mass ratio of anhydrous ethanol to water is 70:1.5, the silane coupling agent is pre-dissolved in anhydrous ethanol, and the mass ratio of silane coupling agent to anhydrous ethanol is 5:12;

[0050] Step b: Add modified material 1 to toluene, add glycidyl methacrylate and the polymerization inhibitor hydroquinone at 220 rpm, heat to 75°C, add benzoyl peroxide under a nitrogen atmosphere, react for 2.5 hours, centrifuge the reaction solution at 4000 rpm for 7 minutes, discard the supernatant, add acetone to the solid precipitate, and wash for 13 minutes. Repeat the centrifugation-washing operation twice, and dry at 52°C for 2.2 hours to obtain modified material 2; wherein, the mass ratio of modified material 1, toluene, glycidyl methacrylate, polymerization inhibitor hydroquinone, and benzoyl peroxide is 100:220:7:0.07:0.15;

[0051] Step c: Disperse modified material 2 in deionized water, add emulsifier sodium dodecyl sulfate, heat to 75℃ and rotate at 450 rpm, add butyl acrylate, methyl methacrylate, crosslinking agent ethylene glycol dimethacrylate and potassium persulfate aqueous solution, react for 2.2 hours, add tert-butyl hydrogen peroxide, keep at 70℃ for 40 minutes, cool to 45℃, add composite coagulant solution under stirring for coagulation, coagulation time is 45 minutes, then filter, wash with deionized water, dry at 55℃ for 5 hours, pulverize, and pass through a 300-mesh sieve to obtain the final product. The mass ratio of modified material 2, deionized water, emulsifier sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, potassium persulfate, and tert-butyl hydroperoxide is 100:350:2:20:14:0.5:0.3:0.2. In the potassium persulfate aqueous solution, the mass ratio of potassium persulfate to deionized water is 0.3:12. In the composite coagulant solution, the concentration of calcium chloride is 3‰ and the concentration of sodium sulfate is 15‰. The mass-to-volume ratio of modified material 2 to composite coagulant solution is 100g / 400mL.

[0052] The preparation method of the above-mentioned composite material for cylindrical shells specifically includes:

[0053] The first step involves mixing the composite modified epoxy resin and the composite modified MBS toughening agent at 65°C and 500 rpm for 50 minutes, then cooling the mixture to 55°C. Next, add the UV absorber, antioxidant, thixotropic agent, and solvent acetone sequentially. The amount of acetone used is 8-15% of the mass of the composite modified epoxy resin. Continue stirring for 40 minutes, then cool the mixture to 45°C, add the curing agent and accelerator, and stir at 350 rpm for 25 minutes to obtain the resin solution.

[0054] The second step involves drying the alkali-free glass fiber roving in an oven at 80±2℃ for 2 hours to remove surface-adsorbed moisture. After cooling to room temperature, the tension is controlled at 0.5-1.0N per bundle of yarn before introducing it into the subsequent impregnation station. This ensures that the fibers are neatly arranged and not loose. Then, the resin solution is placed in the impregnation tank, with the tank temperature controlled at 45-50℃. The fibers pass through the impregnation tank at a speed of 0.8-1.2m / min, and the impregnation time is ≥30 seconds to ensure that the monofilaments are fully wetted, thus obtaining the prepreg.

[0055] The third step is to place the prepreg into the mold and heat-press it for curing. First, keep it at 4MPa and 85℃ for 20 minutes, and then keep it at 110℃ and 15MPa for 35 minutes to allow the resin to cure completely.

[0056] The fourth step is to cool the material down to below 60°C, open the mold, remove the blank, and then perform a post-curing treatment at 145°C for 2.5 hours in an oven to obtain the final product.

[0057] Example 2

[0058] A composite material for cylindrical shells comprises the following components by weight: 100 parts of composite modified epoxy resin, 25 parts of composite modified MBS toughening agent, 25 parts of curing agent, 2 parts of accelerator, 0.5 parts of ultraviolet absorber, 0.8 parts of antioxidant, 1 part of thixotropic agent, and 220 parts of alkali-free glass fiber roving; wherein the curing agent is methyltetrahydrophthalic anhydride, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, the ultraviolet absorber is UV-531, the antioxidant is antioxidant 1010, and the thixotropic agent is fumed silica;

[0059] The preparation method of the composite modified epoxy resin includes the following steps:

[0060] Step 1: At 115°C, with a stirring speed of 250 rpm, and under a nitrogen atmosphere, carboxyl-terminated nitrile butadiene rubber and liquid polysulfide rubber are added to bisphenol A type epoxy resin and reacted for 2.5 hours; wherein the mass ratio of bisphenol A type epoxy resin, carboxyl-terminated nitrile butadiene rubber, and liquid polysulfide rubber is 100:12:1.

[0061] Step 2: Cool the resin after the reaction in Step 1 to 60°C, add bisphenol F epoxy resin and silane coupling agent KH-550 sequentially at 150 rpm, heat to 73°C under a nitrogen atmosphere, and react for 3 hours to obtain silane-modified resin; wherein, the mass ratio of the resin after the reaction in Step 1, bisphenol F epoxy resin, and silane coupling agent is 100:40:4.

[0062] Step 3: The silane-modified resin obtained in Step 2 is heated to 78°C, and hydrophobic fumed silica and titanate coupling agent are added sequentially. The mixture is sheared at 4000 rpm for 10 minutes, during which cooling water is circulated to maintain the reactor temperature ≤80°C. The temperature is then raised to 83°C, and shearing is continued at 4500 rpm for 30 minutes. After shearing, the mixture is degassed for 30 minutes under a vacuum of ≤200 mbar and a temperature of 65°C. The mass ratio of the silane-modified resin, fumed silica, and titanate coupling agent is 100:6:2.5.

[0063] Step 4: Mix methyl methacrylate, butyl acrylate, and benzoyl peroxide evenly to obtain mixture A. Mix methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile evenly to obtain mixture B. Add the polymerization inhibitor p-hydroxyanisole to the resin obtained after degassing in Step 3 at 68℃ and 600 rpm, and stir for 12 minutes. Then, under nitrogen protection, add solution A dropwise at a rate of 25 mL / min. After the addition is complete, react for 90 minutes, then add solution B dropwise at a rate of 15 mL / min. The reaction was continued for 2 hours to obtain acrylate grafted resin; wherein, in mixture A, the mass ratio of methyl methacrylate, butyl acrylate, and benzoyl peroxide was 9:6.5:0.075, and in mixture B, the mass ratio of methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile was 9:6.5:0.075:0.03; and the mass ratio of the resin obtained after degassing in step 3, the polymerization inhibitor p-hydroxyanisole, the methyl methacrylate in mixture A, and the methyl methacrylate in mixture B was 100:0.12:11:9.

[0064] Step 5: Cool the acrylate grafted resin obtained in Step 4 to 70°C, and add the silicone leveling agent, isophorone diisocyanate (65% of the total isophorone diisocyanate content), and catalyst dibutyltin dilaurate sequentially at 300 rpm. React at 78°C for 30 minutes under nitrogen protection. Add the remaining isophorone diisocyanate, 1,4-butanediol, diethylene glycol, and triethyl phosphate, and continue the reaction at 80°C for 70 minutes. Then, at 80°C and a vacuum degree ≤5mb, the reaction is completed. Triethyl phosphate and other volatiles were removed under AR conditions for 33 minutes. After filtration through a 5μm filter bag, the product was aged at 50±2℃ and a vacuum of 0.09MPa for 2.2 hours to obtain the final product. The mass ratio of the acrylate grafted resin, silicone leveling agent, total isophorone diisocyanate, dibutyltin dilaurate, 1,4-butanediol, diethylene glycol, and triethyl phosphate was 100:1.0:9:0.09:3:2.0:0.4.

[0065] The preparation method of the composite modified MBS toughening agent includes the following steps:

[0066] Step a: First, pretreat the MBS powder. Add the pretreated MBS powder to the mixed solvent, adjust the pH to 5.2-5.5 with 0.1% acetic acid, heat to 76℃, and at 300 rpm, dissolve the silane coupling agent KH-570 in anhydrous ethanol beforehand, then slowly add it dropwise to the MBS powder mixture at a rate of 22 mL / min. After the addition is complete, react for 2 hours, cool to 45℃, and neutralize with triethylamine to a pH of 6.5-7.0. Then, at 5000... Centrifuge at rpm for 6 minutes, discard the supernatant, wash twice with anhydrous ethanol, and dry at 55°C for 1.5 hours to obtain modified material 1; wherein, the mass ratio of the pretreated MBS powder, silane coupling agent KH-570, and mixed solvent is 100:4:75, the mass ratio of anhydrous ethanol to water in the mixed solvent is 80:2, the silane coupling agent is pre-dissolved in anhydrous ethanol, and the mass ratio of silane coupling agent to anhydrous ethanol is 6:10; the pretreatment method for MBS powder is the same as in Example 1;

[0067] Step b: Add modified material 1 to toluene, add glycidyl methacrylate and the polymerization inhibitor hydroquinone at 250 rpm, heat to 72°C, add benzoyl peroxide under a nitrogen atmosphere, react for 2.7 hours, and centrifuge and dry (same as in Example 1) to obtain modified material 2; wherein, the mass ratio of modified material 1, toluene, glycidyl methacrylate, polymerization inhibitor hydroquinone, and benzoyl peroxide is 100:250:6:0.08:0.18;

[0068] Step c: Disperse modified material 2 in deionized water, add emulsifier sodium dodecyl sulfate, heat to 76℃ and rotate at 400 rpm, add butyl acrylate, methyl methacrylate, crosslinking agent ethylene glycol dimethacrylate and potassium persulfate aqueous solution, react for 2 hours, add tert-butyl hydrogen peroxide, keep at 68℃ for 35 minutes, cool to 40℃, add composite coagulant solution under stirring for coagulation, coagulation time is 50 minutes, then filter, wash with deionized water, dry at 60℃ for 4.5 hours, pulverize, and pass through a 300-mesh sieve to obtain the final product. The mass ratio of the modified material 2, deionized water, emulsifier sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, potassium persulfate, and tert-butyl hydroperoxide is 100:400:1.5:22:12:0.6:0.25:0.25. In the potassium persulfate aqueous solution, the mass ratio of potassium persulfate to deionized water is 0.25:15. In the composite coagulant solution, the concentration of calcium chloride is 4‰ and the concentration of sodium sulfate is 18‰. The mass-to-volume ratio of the modified material 2 to the composite coagulant solution is 100g / 300mL.

[0069] The preparation method of the above-mentioned composite material for cylindrical shells is the same as that in Example 1.

[0070] Example 3

[0071] A composite material for cylindrical shells comprises the following components by weight: 100 parts of composite modified epoxy resin, 12-25 parts of composite modified MBS toughening agent, 25-35 parts of curing agent, 0.5-2 parts of accelerator, 0.5-1.5 parts of ultraviolet absorber, 0.3-0.8 parts of antioxidant, 1-3 parts of thixotropic agent, and 180 parts of alkali-free glass fiber roving; wherein the curing agent is methyltetrahydrophthalic anhydride, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, the ultraviolet absorber is UV-531, the antioxidant is antioxidant 1010, and the thixotropic agent is fumed silica;

[0072] The preparation method of the composite modified epoxy resin includes the following steps:

[0073] Step 1: At 125°C, with a stirring speed of 200 rpm, and under a nitrogen atmosphere, carboxyl-terminated nitrile butadiene rubber and liquid polysulfide rubber are added to bisphenol A type epoxy resin and reacted for 1.5 hours; wherein the mass ratio of bisphenol A type epoxy resin, carboxyl-terminated nitrile butadiene rubber, and liquid polysulfide rubber is 100:8:3.

[0074] Step 2: Cool the resin after the reaction in Step 1 to 70°C, add bisphenol F epoxy resin and silane coupling agent KH-550 sequentially at 200 rpm, heat to 78°C under a nitrogen atmosphere, and react for 2 hours to obtain silane-modified resin; wherein, the mass ratio of the resin after the reaction in Step 1, bisphenol F epoxy resin, and silane coupling agent is 100:35:6.

[0075] Step 3: The silane-modified resin obtained in Step 2 is heated to 82°C, and hydrophobic fumed silica and titanate coupling agent are added sequentially. The mixture is sheared at 3500 rpm for 15 minutes, during which cooling water is circulated to maintain the reactor temperature ≤80°C. Then, the temperature is raised to 88°C, and shearing is continued at 4000 rpm for 40 minutes. After shearing, the mixture is degassed for 40 minutes under a vacuum of ≤200 mbar and a temperature of 57°C. The mass ratio of the silane-modified resin, fumed silica, and titanate coupling agent is 100:10:1.5.

[0076] Step 4: Mix methyl methacrylate, butyl acrylate, and benzoyl peroxide evenly to obtain mixture A. Mix methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile evenly to obtain mixture B. Add the polymerization inhibitor p-hydroxyanisole to the resin obtained after degassing in Step 3 at 75℃ and 500 rpm, and stir for 8 minutes. Then, under nitrogen protection, add solution A dropwise at a rate of 20 mL / min. After the addition is complete, react for 60 minutes, then add solution B dropwise at a rate of 20 mL / min. After the reaction is completed, the reaction continues for 1.5 hours to obtain acrylate grafted resin; wherein, in the mixture A, the mass ratio of methyl methacrylate, butyl acrylate, and benzoyl peroxide is 11:5:0.1, and in the mixture B, the mass ratio of methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile is 11:5:0.1:0.02; and the mass ratio of the resin obtained after degassing in step 3, the polymerization inhibitor p-hydroxyanisole, the methyl methacrylate in mixture A, and the methyl methacrylate in mixture B is 100:0.08:9:11.

[0077] Step 5: Cool the acrylate grafted resin obtained in Step 4 to 60°C, and add the silicone leveling agent, isophorone diisocyanate (70% of the total isophorone diisocyanate content), and catalyst dibutyltin dilaurate sequentially at 350 rpm. React at 72°C for 40 minutes under nitrogen protection. Add the remaining isophorone diisocyanate, 1,4-butanediol, diethylene glycol, and triethyl phosphate, and continue the reaction at 75°C for 100 minutes. Then, at 75°C and a vacuum degree ≤5 mba, the reaction is completed. Under the r condition, triethyl phosphate and other volatiles are removed for 35-35 minutes. After filtration through a 5μm filter bag, it is cured at 50±2℃ and a vacuum of 0.09MPa for 2.2 hours to obtain the product. The mass ratio of the acrylate grafted resin, silicone leveling agent, total isophorone diisocyanate, dibutyltin dilaurate, 1,4-butanediol, diethylene glycol, and triethyl phosphate is 100:0.5:13:0.06:5:1.0:0.7.

[0078] The preparation method of the composite modified MBS toughening agent includes the following steps:

[0079] Step a: First, pretreat the MBS powder. Add the pretreated MBS powder to the mixed solvent, adjust the pH to 5.2-5.5 with 0.1% acetic acid, heat to 72℃, and at 400 rpm, dissolve the silane coupling agent KH-570 in anhydrous ethanol beforehand, then slowly add it dropwise to the MBS powder mixture at a rate of 28 mL / min. After the addition is complete, react for 2.5 hours, cool to 55℃, and neutralize with triethylamine to a pH of 6.5-7.0. Centrifuge at 3000 rpm for 8 minutes, discard the supernatant, wash twice with anhydrous ethanol, and dry at 45°C for 2 hours to obtain modified material 1; the mass ratio of the pretreated MBS powder, silane coupling agent KH-570, and mixed solvent is 100:6:50, the mass ratio of anhydrous ethanol to water in the mixed solvent is 50:1, the silane coupling agent is pre-dissolved in anhydrous ethanol, and the mass ratio of silane coupling agent to anhydrous ethanol is 4:15; the pretreatment method for MBS powder is the same as in Example 1;

[0080] Step b: Add modified material 1 to toluene, add glycidyl methacrylate and the polymerization inhibitor hydroquinone at 200 rpm, heat to 78°C, add benzoyl peroxide under a nitrogen atmosphere, react for 2.2 hours, and centrifuge and dry (same as in Example 1) to obtain modified material 2; wherein, the mass ratio of modified material 1, toluene, glycidyl methacrylate, polymerization inhibitor hydroquinone, and benzoyl peroxide is 100:200:8:0.05:0.12;

[0081] Step c: Disperse modified material 2 in deionized water, add emulsifier sodium dodecyl sulfate, heat to 72℃ and rotate at 500 rpm, add butyl acrylate, methyl methacrylate, crosslinking agent ethylene glycol dimethacrylate and potassium persulfate aqueous solution, react for 2.5 hours, add tert-butyl hydrogen peroxide, keep at 72℃ for 45 minutes, cool to 50℃, add composite coagulant solution under stirring for coagulation, coagulation time is 40 minutes, then filter, wash with deionized water, dry at 50℃ for 5.5 hours, pulverize, and pass through a 300-mesh sieve to obtain the final product. The mass ratio of the modified material 2, deionized water, emulsifier sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, potassium persulfate, and tert-butyl hydroperoxide is 100:300:2.2:18:16:0.3:0.35:0.15. In the potassium persulfate aqueous solution, the mass ratio of potassium persulfate to deionized water is 0.35:10. In the composite coagulant solution, the concentration of calcium chloride is 2‰ and the concentration of sodium sulfate is 12‰. The mass-to-volume ratio of the modified material 2 to the composite coagulant solution is 100g / 350mL.

[0082] The preparation method of the above-mentioned composite material for cylindrical shells is the same as that in Example 1.

[0083] Comparative Example 1

[0084] A composite material for cylindrical shells, wherein the composite modified epoxy resin is replaced with bisphenol A type epoxy resin, and the rest is the same as in Example 1.

[0085] Comparative Example 2

[0086] A composite material for cylindrical shells, wherein the composite modified MBS toughening agent is replaced with ordinary commercially available MBS powder, and the rest is the same as in Example 1.

[0087] Comparative Example 3

[0088] A composite material for cylindrical shells, wherein the composite modified epoxy resin is replaced with bisphenol A type epoxy resin, and the composite modified MBS toughening agent is replaced with ordinary commercially available MBS powder, the rest being the same as in Example 1.

[0089] Performance testing:

[0090] The impact resistance of the composite materials obtained in Examples 1-3 and Comparative Examples 1-3 was tested in accordance with GB / T 1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams".

[0091] The aging resistance of the composite materials obtained in Examples 1-3 and Comparative Examples 1-3 was tested (70°C / 95% RH, 240h) in accordance with GB / T 2573-2008 "Test Method for Aging Performance of Glass Fiber Reinforced Plastics".

[0092] The tensile strength and elongation at break of the composite materials obtained in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 1447-2005 "Test Method for Tensile Properties of Fiber Reinforced Plastics". The compressive stress of the materials was tested according to the method specified in GB / T 5258-2008.

[0093] The composite materials obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to compressive strength tests perpendicular to the fiber direction, according to standard ASTM D6641, using a universal testing machine (instron 34TM-50).

[0094] The test results are shown in Table 1.

[0095] Table 1. Performance Test Results

[0096]

[0097] From Table 1 and Figure 1 , Figure 2As can be seen, the tensile strength, elongation at break, impact strength, compressive strength, and tensile strength retention rate after damp heat aging of the composite materials obtained in Examples 1-3 are significantly better than those of Comparative Examples 1-3. This indicates that the synergistic effect of the composite modified epoxy resin and the composite modified MBS toughening agent effectively improves the comprehensive performance of the composite material, especially in terms of toughness, interfacial bonding, and resistance to damp heat aging. The tensile strength and elongation at break results show that the composite materials of Examples 1-3 can withstand greater stress during tensile testing while also absorbing energy through a certain degree of plastic deformation, exhibiting a "strength-toughness balance." The tensile strength of Comparative Examples 1-3 is only 420-410 MPa, and the elongation at break is as low as 1.9%-2.6%. This is because the composite modified epoxy resin, by introducing carboxyl-terminated butadiene-acrylonitrile rubber, liquid polysulfide rubber, and polyurethane blocks, reduces the matrix crosslinking density and introduces flexible segments, thereby improving the matrix toughness. Simultaneously, the silane coupling agent enhances the interfacial bonding between the resin and glass fiber, enabling effective stress transfer to the fiber. The composite modified MBS toughening agent, through core-shell structure design and surface modification, forms a good compatibility and chemical bonding interface with epoxy resin, further strengthening the interfacial bonding force. The synergistic effect of both allows the examples to exert the reinforcing effect of fibers during tensile testing, while also enhancing impact resistance through the synergistic effect of the matrix and toughening agent. Moist heat stability: The average tensile strength retention rate of the examples was 91.7%, with Example 3 showing the best retention rate at 94%, a 20.5% increase compared to Comparative Example 1 (78%). Examples 1-3 maintained over 90% of their performance after moist heat aging. This is due to the hydrophobic components in the composite modified epoxy resin and the stable interfacial layer of the composite modified MBS toughening agent, which effectively prevents the penetration and erosion of water molecules.

[0098] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0099] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite material for cylindrical shells, characterized in that, The product comprises the following components by weight: 100 parts of composite modified epoxy resin, 12-25 parts of composite modified MBS toughening agent, 25-35 parts of curing agent, 0.5-2 parts of accelerator, 0.5-1.5 parts of ultraviolet absorber, 0.3-0.8 parts of antioxidant, 1-3 parts of thixotropic agent, and 180-220 parts of glass fiber. The preparation method of the composite modified epoxy resin includes the following steps: Step 1: Add carboxyl-terminated butadiene-acrylonitrile rubber and liquid polysulfide rubber to bisphenol A type epoxy resin at 115-125℃, stirring speed 200-250rpm, and under a nitrogen atmosphere, and react for 1.5-2.5 hours. Step 2: Bisphenol F epoxy resin and silane coupling agent are added sequentially to the resin after the reaction in Step 1. The mixture is heated to 73-78°C under a nitrogen atmosphere and reacted for 2-3 hours to obtain silane-modified resin. Step 3: Heat the silane-modified resin obtained in Step 2 to 78-82℃, add hydrophobic fumed silica and titanate coupling agent in sequence, and perform shear degassing treatment. Step 4: Mix methyl methacrylate, butyl acrylate, and benzoyl peroxide evenly to obtain mixture A. Mix methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile evenly to obtain mixture B. Add polymerization inhibitor, solution A, and solution B to the resin obtained in step 3 and react to obtain acrylate grafted resin. Step 5: Add organosilicon leveling agent, part of isophorone diisocyanate and catalyst to the acrylate grafted resin obtained in Step 4, and react at 72-78℃ for 30-40 minutes under a nitrogen atmosphere. Add the remaining isophorone diisocyanate, 1,4-butanediol, diethylene glycol and triethyl phosphate, and continue to react at 75-80℃ for 70-100 minutes to obtain the final product.

2. The composite material for cylindrical shells according to claim 1, characterized in that, In step 1, the mass ratio of bisphenol A type epoxy resin, carboxyl-terminated nitrile rubber, and liquid polysulfide rubber is 100:8-12:1-3; in step 2, the mass ratio of the resin after reaction in step 1, bisphenol F type epoxy resin, and silane coupling agent is 100:35-40:4-6.

3. The composite material for cylindrical shells according to claim 1, characterized in that, In step 3, the mass ratio of the silane-modified resin, fumed silica, and titanate coupling agent is 100:6-10:1.5-2.

5.

4. The composite material for cylindrical shells according to claim 1, characterized in that, In step 4, the mass ratio of methyl methacrylate, butyl acrylate, and benzoyl peroxide in mixture A is 9-11:5-6.5:0.075-0.1, and the mass ratio of methyl methacrylate, butyl acrylate, benzoyl peroxide, and azobisisobutyronitrile in mixture B is 9-11:5-6.5:0.075-0.1:0.02-0.

03. The mass ratio of the resin obtained after degassing in step 3, the polymerization inhibitor, methyl methacrylate in mixture A, and methyl methacrylate in mixture B is 100:0.08-0.12:9-11:9-11.

5. The composite material for cylindrical shells according to claim 1, characterized in that, In step 5, the mass ratio of the acrylate grafted resin, silicone leveling agent, total amount of isophorone diisocyanate, catalyst, 1,4-butanediol, diethylene glycol, and triethyl phosphate is 100:0.5-1.0:9-13:0.06-0.09:3-5:1.0-2.0:0.4-0.

7.

6. The composite material for cylindrical shells according to claim 1, characterized in that, The preparation method of the composite modified MBS toughening agent includes the following steps: Step a: First, pretreat the MBS powder. Add the pretreated MBS powder to a mixed solvent, adjust the pH to 5.2-5.5, heat to 72-76℃, add silane coupling agent KH-570 at 300-400 rpm, react for 2-2.5 hours, cool to 45-55℃, adjust the pH to 6.5-7.0, purify, and obtain modified material 1. Step b: Add modified material 1 to toluene, add glycidyl methacrylate and the polymerization inhibitor hydroquinone at 200-250 rpm, heat to 72-78℃, add benzoyl peroxide under nitrogen atmosphere, react for 2.2-2.7 hours, purify to obtain modified material 2; Step c: Disperse modified material 2 in deionized water, add emulsifier sodium dodecyl sulfate, heat to 72-76℃ and rotate at 400-500 rpm, add butyl acrylate, methyl methacrylate, crosslinking agent ethylene glycol dimethacrylate and potassium persulfate aqueous solution, react for 2-2.5 hours, add tert-butyl hydrogen peroxide, keep at 68-72℃ for 35-45 minutes, cool to 40-50℃, add composite coagulant solution under stirring to coagulate, and purify to obtain the final product.

7. The composite material for cylindrical shells according to claim 6, characterized in that, In step a, the mass ratio of the pretreated MBS powder, silane coupling agent KH-570, and mixed solvent is 100:4-6:50-75, and the mass ratio of anhydrous ethanol and water in the mixed solvent is 50-80:1-2.

8. The composite material for cylindrical shells according to claim 6, characterized in that, In step b, the mass ratio of the modified material 1, toluene, glycidyl methacrylate, polymerization inhibitor hydroquinone, and benzoyl peroxide is 100:200-250:6-8:0.05-0.08:0.12-0.

18.

9. The composite material for cylindrical shells according to claim 6, characterized in that, In step c, the mass ratio of the modified material 2, deionized water, emulsifier sodium dodecyl sulfate, butyl acrylate, methyl methacrylate, ethylene glycol dimethacrylate, potassium persulfate, and tert-butyl hydroperoxide is 100:300-400:1.5-2.2:18-22:12-16:0.3-0.6:0.25-0.35:0.15-0.

25. In the potassium persulfate aqueous solution, the mass ratio of potassium persulfate to deionized water is 0.25-0.35:10-15. In the composite coagulant solution, the concentration of calcium chloride is 2-4‰ and the concentration of sodium sulfate is 12-18‰.

10. The method for preparing the composite material for cylindrical shells as described in any one of claims 1-9, characterized in that, Specifically, it includes: The first step involves mixing the composite modified epoxy resin, composite modified MBS toughening agent, ultraviolet absorber, antioxidant, thixotropic agent, solvent, curing agent, and accelerator to obtain a resin solution. The second step involves controlling the glass fiber tension to 0.5-1.0N per bundle of yarn, setting the glue bath temperature to 45-50℃, placing the resin solution into the glue bath, and allowing the glass fiber to pass through the glue bath at a speed of 0.8-1.2m / min for a immersion time of ≥30 seconds to obtain the prepreg. The third step is to place the prepreg into the mold and heat-press it for curing. The fourth step is to perform post-curing treatment after demolding to obtain the final product.

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