High-strength carbon fiber plate and processing technology thereof

Abstract

The application relates to a high-strength carbon fiber plate and a processing technology thereof, and relates to the technical field of carbon fiber composite materials. The preparation raw materials comprise carbon fiber cloth and slurry, and the slurry comprises the following components in mass fractions: coupling agent modified epoxy resin, 30-40 parts, polyimide prepolymer, 20-30 parts, bismaleimide monomer, 15-25 parts, acyl chloride modified carbon nanotube, 3-5 parts, curing agent, 8-12 parts, diluent, 5-10 parts, antioxidant, 1-2 parts and ultraviolet light absorber, 1-2 parts. The processing technology comprises the following steps: carbon fiber cloth is immersed into the slurry, pressure is applied during the immersion process, and a prepreg is obtained; the prepreg is heated and dried to obtain a preliminarily cured prepreg; the preliminarily cured prepreg is cut and placed into a mold for hot press forming, and after cooling, the mold is demolded to obtain the high-strength carbon fiber plate. The application has the effect of improving the strength and thermal stability of the carbon fiber plate, and the high-strength carbon fiber plate can maintain good working performance for a long time in a complex and harsh environment.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon fiber composite materials, in particular to a high-strength carbon fiber plate and a processing technology thereof. BACKGROUND

[0002] Carbon fibers have a high strength-to-weight ratio, with a tensile strength reaching several gigapascals, far exceeding traditional metal materials such as steel and aluminum, and a density of only about one-fourth of that of steel. In the field of aerospace, the use of carbon fiber materials by aircraft can significantly reduce the weight of the structure, thereby reducing fuel consumption and increasing the payload, opening up new paths for space exploration and long-distance flight. Carbon fibers have excellent corrosion resistance and can serve in harsh chemical environments such as acid, alkali, moisture and even the ocean for a long time. In the application scenarios of deep-sea exploration equipment and offshore wind power facilities in marine engineering, carbon fibers can effectively resist seawater erosion, reduce maintenance costs and prolong the service life of equipment. Carbon fibers have excellent high-temperature resistance and can withstand high temperatures of several thousand degrees Celsius. In high-temperature working conditions such as hot end parts of aircraft engines and high-temperature industrial furnace linings, the stability and mechanical properties of the material are maintained to ensure the safe and efficient operation of key systems.

[0003] However, when carbon fibers are converted into carbon fiber plates in this application form, many strength-related problems are exposed. Although the strength of the carbon fiber filament itself is considerable, there may be problems with poor interfacial bonding during the compounding process with the resin matrix. Some resins have a large curing shrinkage rate, which will generate internal stress with the carbon fibers after curing, causing microcracks in the interface. These cracks become stress concentration points, severely weakening the overall strength of the carbon fiber plate, and thus need to be improved. SUMMARY

[0004] In order to improve the strength of the carbon fiber plate, the application provides a high-strength carbon fiber plate and a processing technology thereof.

[0005] The high-strength carbon fiber plate and the processing technology thereof provided by the application adopt the following technical scheme:

[0006] In a first aspect, the high-strength carbon fiber plate provided by the application adopts the following technical scheme:

[0007] A high-strength carbon fiber plate, the preparation raw materials include carbon fiber cloth and slurry, the slurry includes the following components in mass fraction: coupling agent modified epoxy resin 30-40 parts

[0008] Polyimide prepolymer 20-30 parts

[0009] Bismaleimide monomer 15-25 parts

[0010] Acyl chloride modified carbon nanotube 3-5 parts

[0011] Curing agent 8-12 parts

[0012] Diluent 5-10 parts

[0013] Antioxidant 1-2 parts

[0014] UV absorber 1-2 parts.

[0015] The coupling agent modified epoxy resin can form chemical bonding with the carbon fiber cloth at the molecular level by introducing the active groups of the coupling agent, tightly connecting the two, and at the same time using its excellent film-forming properties and adhesion performance to build a solid and continuous matrix structure for the plate, effectively maintaining the overall mechanical integrity, ensuring that each part cooperates to bear the load when stressed, thereby improving the strength of the plate; the polyimide prepolymer has outstanding heat resistance, and under high temperature conditions, various functional groups within its molecules, such as anhydride groups and amino groups, will spontaneously crosslink, and this strengthening process of the crosslinked structure can significantly improve the thermal stability of the material, effectively resisting problems such as softening and deformation caused by high temperatures, ensuring the structural reliability and performance stability of the plate in high temperature environments, thereby improving the strength of the plate; the bismaleimide monomer contains two highly active maleimide functional groups, which can chemically react with other resin components during the polymerization process, significantly increasing the crosslinking density of the resin system, and thereby optimizing the internal network structure of the material, significantly improving the strength and modulus of the plate to meet the needs of high-strength application scenarios; the acyl chloride modified carbon nanotube has a good chemical reactivity of the acyl chloride group on its surface, which can form stable connections with active groups in the resin through covalent bonds, optimizing the interface bonding state between different components, enabling efficient load transfer between components, and improving the overall mechanical properties and strength from a microscopic perspective.

[0016] Preferably, the preparation raw materials of the coupling agent modified epoxy resin include bisphenol A type epoxy resin, N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane.

[0017] The bisphenol A type epoxy resin has good mechanical properties, provides basic strength support for the plate, and the epoxy groups in the molecule can participate in crosslinking reaction to build a stable resin network structure; the amino group of N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane can form chemical bonding with the oxygen-containing functional groups on the surface of the carbon fiber, and the siloxane group after hydrolysis can be closely connected with the epoxy resin, thereby bridging to strengthen the interfacial bonding force between the carbon fiber and the resin matrix, enabling the external force to be more efficiently transmitted from the carbon fiber to the resin matrix, and the overall strength is improved; the mercapto group in 3-mercaptopropyl triethoxysilane can participate in the curing reaction of the epoxy resin, optimize the crosslinking network, and enhance the cohesive force of the resin matrix; at the same time, the silane part improves the compatibility of the epoxy resin with other components, reduces the internal stress concentration; under high temperature environment, the coupling agent modified epoxy resin system can effectively inhibit the thermal motion of molecular chain and hinder the thermal degradation process by means of close and stable chemical bonding and optimized crosslinking structure, thereby significantly improving the thermal stability of the material and ensuring the reliable performance of the high-strength carbon fiber plate under severe thermal working conditions.

[0018] Preferably, the coupling agent modified epoxy resin is prepared by the following steps:

[0019] N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane and 3-mercaptopropyl triethoxysilane are mixed and dispersed in ethanol to obtain a coupling agent solution; the coupling agent solution is added to the bisphenol A type epoxy resin, and the reaction is stirred under heating, and the solvent is removed by rotary evaporation to obtain the coupling agent modified epoxy resin.

[0020] The carbon fiber plate prepared according to the above steps has high strength and good thermal stability, and can maintain good working performance for a long time under complex environmental conditions.

[0021] Preferably, the raw materials for preparing the polyimide prepolymer include a composite diamine monomer and 3,3',4,4'-benzophenonetetracarboxylic dianhydride.

[0022] The active amino groups in the composite diamine monomer can rapidly undergo nucleophilic addition reactions with the anhydride groups in the 3,3',4,4'-benzophenone tetracarboxylic dianhydride molecule at the beginning of the polymerization reaction. As the reaction progresses, a regular and long-chain polyimide molecular structure is gradually formed. This long-chain structure is intertwined and entangled, which greatly improves the intrinsic strength of the material. When the board is subjected to external forces, the stable structure formed by the polyimide can effectively disperse stress and avoid local concentrated fracture. The rigid benzene ring structure and strong hydrogen bonding formed in the polyimide molecular chain endow the material with excellent thermal stability. Under high temperature environment, the rigid benzene ring can restrict the free rotation of the molecular chain, while the strong hydrogen bonds prevent the relative slippage between the molecular chains. The two work together to effectively suppress the thermal deformation of the material, so that the high-strength carbon fiber board can maintain a stable structure and performance even under harsh thermal conditions, thus improving the thermal stability of the carbon fiber board.

[0023] Preferably, the composite diamine monomer comprises 4,4'-diaminodiphenyl ether and 1,3-bis(4-aminophenoxy)benzene.

[0024] 4,4'-Diaminodiphenyl ether possesses a symmetrical and regular molecular structure. Its amino group can react efficiently with 3,3',4,4'-benzophenone tetracarboxylic dianhydride to construct a stable initial molecular chain structure, giving the material initial strength. The phenoxy structure of 1,3-bis(4-aminophenoxy)benzene breaks the conventional tight packing of molecular chains, giving the molecular chain flexibility. Under stress, the two work together, with the rigid chain segment dominated by 4,4'-diaminodiphenyl ether serving as the core load-bearing structure, strongly supporting external forces. The flexible phenoxy group of phenoxybenzene acts as a buffer, flexibly adjusting the relative positions between molecular chains, uniformly dispersing stress, reducing the risk of material fracture, and synergistically improving strength. In high-temperature environments, the rigid benzene ring of 4,4'-diaminodiphenyl ether and the rigid part of 1,3-bis(4-aminophenoxy)benzene jointly regulate the thermal motion of molecular chains, and the flexible phenoxy group alleviates the internal stress caused by thermal expansion and contraction. Furthermore, the strong hydrogen bonds formed within and between the two molecules further strengthen the molecular connection network, stabilize the material structure, and thus improve the thermal stability of the carbon fiber plate.

[0025] Preferably, the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is (0.6-0.7):(0.3-0.4):1.

[0026] The polyimide prepolymer prepared according to the above mass ratio has a good molecular chain structure, which can effectively improve the strength and thermal stability of carbon fiber sheets.

[0027] Preferably, the bismaleimide monomer comprises 4,4'-bismaleimide diphenylmethane.

[0028] The rigid diphenylmethane structure in 4,4'-bismaleimide diphenylmethane serves as its core support, endowing the molecular chain with high rigidity and regularity. During polymerization, the bismaleimide functional groups at both ends can rapidly undergo cross-linking reactions with other resin components in the system, constructing a dense and high-strength three-dimensional network structure, effectively improving the material strength. Under high-temperature conditions, the rigid diphenylmethane and the stable network formed by cross-linking can restrict the thermal motion of the molecular chains, inhibiting the slippage and breakage of the molecular chains, allowing the material to maintain structural integrity under thermal shock, thus improving the thermal stability of the carbon fiber sheet. This highly cross-linked structure also possesses excellent chemical stability, resisting the erosion of complex external chemical environments, comprehensively improving the performance of high-strength carbon fiber sheets, and meeting the demand for high strength and high thermal stability in stringent fields such as aerospace and high-end equipment manufacturing.

[0029] Preferably, the raw materials for preparing the acyl chloride modified carbon nanotubes include carbon nanotube oxide and thionyl chloride.

[0030] The surface of carbon nanotubes is rich in oxygen-containing functional groups. Thionyl chloride, as a strong chlorinating agent, can chemically react with these oxygen-containing functional groups, successfully introducing acyl chloride groups into the surface of carbon nanotubes. In subsequent composite with resin systems, the acyl chloride groups can rapidly react with active groups such as hydroxyl and amino groups in epoxy resins and polyimide prepolymers, forming a tight bond through chemical bonds. This optimizes the interfacial bonding between the two, enabling efficient stress transfer under external forces and greatly enhancing the overall strength of the material. Carbon nanotubes themselves have high strength and high modulus. After modification with acyl chloride, they can be uniformly dispersed in the resin matrix, further strengthening the load-bearing capacity. The excellent thermal conductivity of carbon nanotubes can quickly dissipate heat and avoid local overheating. At the same time, the stable structure formed by their tight bonding with resin can effectively inhibit the thermal motion of molecular chains under high-temperature environments, synergistically resisting thermal degradation and improving the thermal stability of carbon fiber sheets.

[0031] Preferably, the mass ratio of the carbon oxide nanotubes to thionyl chloride is 1:(0.6-0.8).

[0032] The acyl chloride-modified carbon nanotubes prepared according to the above mass ratio have good compatibility and reactivity, and can effectively improve the strength and thermal stability of carbon fiber plates.

[0033] Secondly, this application provides a processing technology for high-strength carbon fiber sheets, employing the following technical solution:

[0034] A processing technology for high-strength carbon fiber sheets includes the following steps:

[0035] Carbon fiber cloth is impregnated into a slurry, and pressure is applied during the impregnation process to obtain a prepreg. The prepreg is heated and dried to obtain a pre-cured prepreg. The pre-cured prepreg is cut and placed into a mold for hot pressing. After cooling, it is demolded to obtain a high-strength carbon fiber sheet.

[0036] The carbon fiber plate prepared according to the above steps has high strength and good thermal stability, and can maintain good working performance for a long time in complex and harsh environments.

[0037] In summary, this application includes at least one of the following beneficial technical effects:

[0038] 1. Coupling agent-modified epoxy resin, by introducing the active groups of the coupling agent, can form chemical bonds with carbon fiber cloth at the molecular level, tightly connecting the two. Simultaneously, utilizing its excellent film-forming properties and adhesion performance, it constructs a solid and continuous matrix structure for the board, effectively maintaining the overall mechanical integrity and ensuring that all parts cooperate in bearing loads, thereby improving the strength of the board. Polyimide prepolymer possesses outstanding heat resistance properties. Under high-temperature conditions, various functional groups within its molecules, such as anhydride and amino groups, spontaneously undergo cross-linking reactions. This cross-linking strengthening process significantly improves the thermal stability of the material, effectively resisting softening and deformation caused by high temperatures, and ensuring the structural reliability of the board in high-temperature environments. The bismaleimide monomer contains two highly active maleimide functional groups, which can react chemically with other resin components during the polymerization process, significantly increasing the crosslinking density of the resin system and optimizing the internal network structure of the material. This results in a significant improvement in the strength and modulus of the sheet, meeting the requirements of high-strength applications. Acyl chloride-modified carbon nanotubes have modified acyl chloride groups on their surface, which have good chemical reactivity and can form stable connections with active groups in the resin system through covalent bonds. This optimizes the interfacial bonding state between different components, enabling efficient load transfer between components and improving the overall mechanical properties and strength at the microscopic level.

[0039] 2. Bisphenol A type epoxy resin possesses excellent mechanical properties, providing basic strength support for the board. The epoxy groups in its molecule can participate in cross-linking reactions, constructing a stable resin network structure. The amino groups of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane can form chemical bonds with the oxygen-containing functional groups on the carbon fiber surface. After hydrolysis, the siloxane groups can tightly connect with the epoxy resin, strengthening the interfacial bonding force between the carbon fiber and the resin matrix through bridging. This allows external forces to be transferred more efficiently from the carbon fiber to the resin matrix, synergistically bearing load and thus improving overall strength. The thiol groups in 3-mercaptopropyltriethoxysilane can participate in the curing reaction of epoxy resin, optimize the crosslinking network, and enhance the cohesive force of the resin matrix. At the same time, the silane portion improves the compatibility of epoxy resin with other components and reduces internal stress concentration. Under high-temperature conditions, the coupling agent-modified epoxy resin system, with its tight and stable chemical bonding and optimized crosslinking structure, can effectively inhibit the thermal motion of molecular chains and hinder the thermal degradation process, thereby significantly improving the thermal stability of the material and ensuring the reliable performance of high-strength carbon fiber sheets under harsh thermal conditions.

[0040] 3. In the composite diamine monomer, 4,4'-diaminodiphenyl ether has a symmetrical and regular molecular structure. Its amino group can react efficiently with 3,3',4,4'-benzophenone tetracarboxylic dianhydride to construct a stable initial molecular chain structure, giving the material initial strength. The phenoxy structure of 1,3-bis(4-aminophenoxy)benzene breaks the conventional tight packing of molecular chains, giving the molecular chain flexibility. Under stress, the two work together, with the rigid chain segment dominated by 4,4'-diaminodiphenyl ether serving as the core load-bearing structure, strongly supporting external forces. The flexible phenoxy group of 4-aminophenoxybenzene acts as a buffer, flexibly adjusting the relative positions between molecular chains, uniformly dispersing stress, reducing the risk of material fracture, and synergistically improving strength. In high-temperature environments, the rigid benzene ring of 4,4'-diaminodiphenyl ether and the rigid part of 1,3-bis(4-aminophenoxy)benzene jointly regulate the thermal motion of molecular chains, and the flexible phenoxy group alleviates the internal stress caused by thermal expansion and contraction. Furthermore, the strong hydrogen bonds formed within and between the two molecules further strengthen the molecular connection network, stabilize the material structure, and thus improve the thermal stability of the carbon fiber plate. Detailed Implementation

[0041] This application discloses a high-strength carbon fiber plate and its processing technology. Unless otherwise specified, all raw materials used in this application are commercially available. The following detailed description, in conjunction with embodiments, further illustrates this application:

[0042] Raw material description: The carbon fiber cloth used in this application is biaxial carbon fiber cloth, bisphenol A epoxy resin (CAS No.: 25085-99-8), N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane (CAS No.: 1760-24-3), 3-mercaptopropyltriethoxysilane (CAS No.: 14814-09-6), 4,4'-diaminodiphenyl ether (CAS No.: 101-80-4), 1,3-bis(4-aminophenoxy)benzene (CAS No.: 2479-46-1), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (CAS No.: 2421-87-3), and multi-walled carbon nanotubes of type XFM34 were purchased from Jiangsu Xianfeng. Nanomaterials Technology Co., Ltd. Thionyl chloride (CAS No.: 7719-09-7), N-methylpyrrolidone (CAS No.: 872-50-4), triethylamine (CAS No.: 121-44-8), bismaleimide monomer 4,4'-bismaleimide diphenylmethane (CAS No.: 13676-54-5), curing agent is amino-terminated polyether (CAS No.: 9046-10-0), diluent is allyl glycidyl ether (CAS No.: 106-92-3), antioxidant is antioxidant 1010 (CAS No.: 6683-19-8), and ultraviolet absorber is UV-327 (CAS No.: 3864-99-1).

[0043] Example 1

[0044] Preparation of coupling agent modified epoxy resin

[0045] 5 kg of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3 kg of 3-mercaptopropyltriethoxysilane were mixed and dispersed in 20 L of anhydrous ethanol and stirred at 200 rpm for 15 min to obtain a coupling agent solution. The coupling agent solution was added to 50 kg of bisphenol A type epoxy resin and added completely within 30 min. After the addition was completed, the temperature was raised to 60 °C and the reaction was stirred at 200 rpm for 2 h. The solvent was removed by rotary evaporation to obtain the coupling agent modified epoxy resin.

[0046] Preparation of polyimide prepolymer

[0047] 4,4'-diaminodiphenyl ether and 1,3-bis(4-aminophenoxy)benzene were mixed and dispersed in N,N-dimethylacetamide and stirred at 200 rpm for 15 min to prepare a 20% (w / w) composite diamine monomer solution. 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added to the composite diamine monomer solution, such that the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride was 0.6:0.4:1. The addition was completed within 1 h. The reaction temperature was controlled at 25 °C, and the reaction was stirred at 300 rpm for 4 h. The solvent was removed by rotary evaporation to obtain the polyimide prepolymer.

[0048] Preparation of acyl chloride modified carbon nanotubes

[0049] 10 kg of multi-walled carbon nanotubes were dispersed in a mixed acid consisting of 30 L of sulfuric acid and 10 L of nitric acid, with a sulfuric acid concentration of 98% and a nitric acid concentration of 70%. The mixture was stirred at 200 rpm for 3 h in an oil bath at 60 °C. The mixture was then filtered and washed with deionized water until the filtrate was neutral. The washed carbon nanotubes were then vacuum dried at 80 °C to obtain carbon oxide nanotubes.

[0050] 6.25 kg of carbon nanotubes and 3.75 kg of thionyl chloride were mixed and dispersed in 20 L of N-methylpyrrolidone. 0.3 kg of triethylamine was added, and the mixture was stirred at 150 rpm for 12 h at 75 °C under nitrogen protection. After cooling to 30 °C, the solvent was removed by rotary evaporation. The product was washed by vacuum filtration with anhydrous ethanol and dried under vacuum at 60 °C to obtain acyl chloride-modified carbon nanotubes.

[0051] Preparation of slurry

[0052] Mix 30 kg of coupling agent-modified epoxy resin, 20 kg of polyimide prepolymer, 15 kg of bismaleimide monomer, and 3 kg of acyl chloride-modified carbon nanotubes, and stir at 300 rpm for 15 min to obtain a premix. Dissolve 8 kg of curing agent in 20 L of anhydrous ethanol to obtain a curing agent solution. Add the curing agent solution to the premix while stirring at 300 rpm during the addition process, and complete the addition within 30 min. Add 5 kg of diluent and continue stirring at 300 rpm for 30 min. Add 1 kg of antioxidant and 1 kg of UV absorber, and stir at 500 rpm for 1 h to obtain a slurry.

[0053] Preparation of high-strength carbon fiber plates

[0054] Carbon fiber cloth is impregnated into a slurry, and a pressure of 0.3 MPa is applied during the impregnation process to obtain a prepreg. The prepreg is dried at 100°C for 1 hour to remove the solvent, resulting in a pre-cured prepreg. The pre-cured prepreg is cut and placed into a mold for hot pressing at 200°C, with a pressure of 6 MPa and a pressing time of 4 hours. After cooling to below 30°C, the prepreg is demolded to obtain a high-strength carbon fiber sheet.

[0055] Example 2

[0056] Preparation of coupling agent modified epoxy resin

[0057] 5 kg of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3 kg of 3-mercaptopropyltriethoxysilane were mixed and dispersed in 20 L of anhydrous ethanol and stirred at 200 rpm for 15 min to obtain a coupling agent solution. The coupling agent solution was added to 50 kg of bisphenol A type epoxy resin and added completely within 30 min. After the addition was completed, the temperature was raised to 60 °C and the reaction was stirred at 200 rpm for 2 h. The solvent was removed by rotary evaporation to obtain the coupling agent modified epoxy resin.

[0058] Preparation of polyimide prepolymer

[0059] 4,4'-diaminodiphenyl ether and 1,3-bis(4-aminophenoxy)benzene were mixed and dispersed in N,N-dimethylacetamide and stirred at 200 rpm for 15 min to prepare a 20% (w / w) composite diamine monomer solution. 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added to the composite diamine monomer solution, such that the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride was 0.7:0.3:1. The addition was completed within 1 h. The reaction temperature was controlled at 25 °C, and the reaction was stirred at 300 rpm for 4 h. The solvent was removed by rotary evaporation to obtain the polyimide prepolymer.

[0060] Preparation of acyl chloride modified carbon nanotubes

[0061] 10 kg of multi-walled carbon nanotubes were dispersed in a mixed acid consisting of 30 L of sulfuric acid and 10 L of nitric acid, with a sulfuric acid concentration of 98% and a nitric acid concentration of 70%. The mixture was stirred at 200 rpm for 3 h in an oil bath at 60 °C. The mixture was then filtered and washed with deionized water until the filtrate was neutral. The washed carbon nanotubes were then vacuum dried at 80 °C to obtain carbon oxide nanotubes.

[0062] 5.56 kg of carbon nanotubes and 4.44 kg of thionyl chloride were mixed and dispersed in 20 L of N-methylpyrrolidone. 0.3 kg of triethylamine was added, and the mixture was stirred at 150 rpm for 12 h at 75 °C under nitrogen protection. After cooling to 30 °C, the solvent was removed by rotary evaporation. The product was washed by vacuum filtration with anhydrous ethanol and dried under vacuum at 60 °C to obtain acyl chloride-modified carbon nanotubes.

[0063] Preparation of slurry

[0064] 40 kg of coupling agent-modified epoxy resin, 30 kg of polyimide prepolymer, 25 kg of bismaleimide monomer, and 5 kg of acyl chloride-modified carbon nanotubes were mixed and stirred at 300 rpm for 15 min to obtain a premix. 12 kg of curing agent was dissolved in 20 L of anhydrous ethanol to obtain a curing agent solution. The curing agent solution was added to the premix while stirring at 300 rpm during the addition process, and the addition was completed within 30 min. 10 kg of diluent was added, and stirring was continued at 300 rpm for 30 min. 2 kg of antioxidant and 2 kg of UV absorber were added, and stirring was carried out at 500 rpm for 1 h to obtain a slurry.

[0065] Preparation of high-strength carbon fiber plates

[0066] Carbon fiber cloth is impregnated into a slurry, and a pressure of 0.3 MPa is applied during the impregnation process to obtain a prepreg. The prepreg is dried at 100°C for 1 hour to remove the solvent, resulting in a pre-cured prepreg. The pre-cured prepreg is cut and placed into a mold for hot pressing at 200°C, with a pressure of 6 MPa and a pressing time of 4 hours. After cooling to below 30°C, the prepreg is demolded to obtain a high-strength carbon fiber sheet.

[0067] Example 3

[0068] Preparation of coupling agent modified epoxy resin

[0069] 5 kg of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3 kg of 3-mercaptopropyltriethoxysilane were mixed and dispersed in 20 L of anhydrous ethanol and stirred at 200 rpm for 15 min to obtain a coupling agent solution. The coupling agent solution was added to 50 kg of bisphenol A type epoxy resin and added completely within 30 min. After the addition was completed, the temperature was raised to 60 °C and the reaction was stirred at 200 rpm for 2 h. The solvent was removed by rotary evaporation to obtain the coupling agent modified epoxy resin.

[0070] Preparation of polyimide prepolymer

[0071] 4,4'-diaminodiphenyl ether and 1,3-bis(4-aminophenoxy)benzene were mixed and dispersed in N,N-dimethylacetamide and stirred at 200 rpm for 15 min to prepare a 20% (w / w) composite diamine monomer solution. 3,3',4,4'-benzophenone tetracarboxylic dianhydride was added to the composite diamine monomer solution, such that the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride was 0.65:0.35:1. The addition was completed within 1 h. The reaction temperature was controlled at 25 °C, and the reaction was stirred at 300 rpm for 4 h. The solvent was removed by rotary evaporation to obtain the polyimide prepolymer.

[0072] Preparation of acyl chloride modified carbon nanotubes

[0073] 10 kg of multi-walled carbon nanotubes were dispersed in a mixed acid consisting of 30 L of sulfuric acid and 10 L of nitric acid, with a sulfuric acid concentration of 98% and a nitric acid concentration of 70%. The mixture was stirred at 200 rpm for 3 h in an oil bath at 60 °C. The mixture was then filtered and washed with deionized water until the filtrate was neutral. The washed carbon nanotubes were then vacuum dried at 80 °C to obtain carbon oxide nanotubes.

[0074] 5.88 kg of carbon nanotubes and 4.12 kg of thionyl chloride were mixed and dispersed in 20 L of N-methylpyrrolidone. 0.3 kg of triethylamine was added, and the mixture was stirred at 150 rpm for 12 h at 75 °C under nitrogen protection. After cooling to 30 °C, the solvent was removed by rotary evaporation. The product was washed with anhydrous ethanol and then dried under vacuum at 60 °C to obtain acyl chloride-modified carbon nanotubes.

[0075] Preparation of slurry

[0076] 35 kg of coupling agent-modified epoxy resin, 25 kg of polyimide prepolymer, 20 kg of bismaleimide monomer, and 4 kg of acyl chloride-modified carbon nanotubes were mixed and stirred at 300 rpm for 15 min to obtain a premix. 10 kg of curing agent was dissolved in 20 L of anhydrous ethanol to obtain a curing agent solution. The curing agent solution was added to the premix while stirring at 300 rpm during the addition process, and the addition was completed within 30 min. 7.5 kg of diluent was added, and stirring was continued at 300 rpm for 30 min. 1.5 kg of antioxidant and 1.5 kg of UV absorber were added, and stirring was carried out at 500 rpm for 1 h to obtain a slurry.

[0077] Preparation of high-strength carbon fiber plates

[0078] Carbon fiber cloth is impregnated into a slurry, and a pressure of 0.3 MPa is applied during the impregnation process to obtain a prepreg. The prepreg is dried at 100°C for 1 hour to remove the solvent, resulting in a pre-cured prepreg. The pre-cured prepreg is cut and placed into a mold for hot pressing at 200°C, with a pressure of 6 MPa and a pressing time of 4 hours. After cooling to below 30°C, the prepreg is demolded to obtain a high-strength carbon fiber sheet.

[0079] Example 4

[0080] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane is not added when preparing the coupling agent modified epoxy resin in Example 4.

[0081] Example 5

[0082] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that 3-mercaptopropyltriethoxysilane is not added when preparing the coupling agent modified epoxy resin in Example 5.

[0083] Example 6

[0084] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in Example 6 is 0.5:0.5:1.

[0085] Example 7

[0086] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in Example 7 is 0.8:0.2:1.

[0087] Example 8

[0088] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that the amount of carbon nanotubes used in Example 8 is 7.14 kg and the amount of thionyl chloride used is 2.86 kg.

[0089] Example 9

[0090] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that the amount of carbon nanotubes used in Example 9 is 5 kg and the amount of thionyl chloride used is 5 kg.

[0091] Example 10

[0092] Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that carbon oxide nanotubes are replaced with carbon nanotubes in Example 10.

[0093] Comparative Example 1

[0094] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the coupling agent modified epoxy resin in Comparative Example 1 is replaced with bisphenol A type epoxy resin.

[0095] Comparative Example 2

[0096] Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that the raw materials for preparing the polyimide prepolymer in Comparative Example 2 are replaced with 4,4'-diaminodiphenyl ether and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in a molar ratio of 1:1.

[0097] Comparative Example 3

[0098] Comparative Example 3 is based on Example 3. The only difference between Comparative Example 3 and Example 3 is that no bismaleimide monomer is added in Comparative Example 3.

[0099] Comparative Example 4

[0100] Comparative Example 4 is based on Example 3. The only difference between Comparative Example 4 and Example 3 is that the acyl chloride modified carbon nanotubes are replaced with carbon nanotubes in Comparative Example 4.

[0101] Performance testing

[0102] (1) The following standards were selected: GB / T1447-2005 Test Method for Tensile Properties of Fiber Reinforced Plastics, GB / T1449-2005 Test Method for Bending Properties of Fiber Reinforced Plastics and GB / T30969-2014 Test Method for Shear Strength of Short Beams of Polymer-Based Composite Materials. The longitudinal strength and modulus of the specimens were tested. Five samples were prepared for each specimen. The average value was taken after measurement and the results were recorded in Table 1 and Table 2.

[0103] (2) The standard GB / T2572-2005 Test Method for Average Linear Expansion Coefficient of Fiber Reinforced Plastics was selected to test the linear expansion coefficient of the specimen. Three samples were prepared for each specimen, and the average value was taken after measurement. The results were recorded in Table 2.

[0104] Table 1. Test results of tensile and flexural properties of carbon fiber sheets

[0105]

[0106]

[0107] Table 2. Test results of tensile and flexural properties of carbon fiber sheets

[0108] Detection results Shear strength (GPa) Shear modulus (GPa) Linear expansion coefficient (10 -6 / K) Example 1 122.34 30.87 1.25 Example 2 122.43 30.95 1.26 Example 3 122.46 31.11 1.23 Example 4 117.62 29.34 1.42 Example 5 116.35 28.97 1.46 Example 6 119.53 29.87 1.33 Example 7 118.69 29.51 1.36 Example 8 118.26 29.85 1.38 Example 9 116.85 28.84 1.47 Example 10 119.33 29.62 1.34 Comparative Example 1 113.84 27.58 1.52 Comparative Example 2 114.36 28.14 1.50 Comparative Example 3 98.75 25.41 2.33 Comparative Example 4 116.24 28.35 1.51

[0109] As shown in Tables 1 and 2, the tensile strength of Examples 1-3 is greater than 1238.24 MPa, the tensile modulus is greater than 89.62 GPa, the flexural strength is greater than 967.35 MPa, the flexural modulus is greater than 78.58 GPa, the shear strength is greater than 122.34 GPa, the shear modulus is greater than 30.87 GPa, and the coefficient of linear expansion is less than 1.26 × 10⁻⁶. -6 / K, thus showing that the carbon fiber plate prepared in this application has high strength and good thermal stability.

[0110] As shown in Tables 1 and 2, the only difference between Examples 4 and 5 and Example 3 is that N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane was not added when preparing the coupling agent modified epoxy resin in Example 4, and 3-mercaptopropyltriethoxysilane was not added when preparing the coupling agent modified epoxy resin in Example 5. Compared with Example 3, the strength and thermal stability of Examples 4 and 5 decreased. This is because reducing the synthetic components in the coupling agent modified epoxy resin will affect the interfacial bonding force and crosslinking density of the epoxy resin, thus reducing the performance of the carbon fiber board.

[0111] As shown in Tables 1 and 2, the only difference between Examples 6 and 7 and Example 3 is that in Example 6, the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 0.5:0.5:1, and in Example 7, the molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 0.8:0.2:1. Compared with Example 3, Examples 6 and 7 show a decrease in strength and thermal stability. This is because the ratio of the polyimide prepolymer was disrupted, and the change in the number of flexible groups affects the stacking and performance of the molecular chains, thereby affecting the microstructure inside the carbon fiber sheet, which in turn affects the strength and thermal stability.

[0112] As shown in Tables 1 and 2, the differences between Examples 8, 9, and 10 and Example 3 are only as follows: in Example 8, the mass ratio of carbon oxide nanotubes to thionyl chloride is 1:0.4; in Example 9, the mass ratio of carbon oxide nanotubes to thionyl chloride is 1:1; and in Example 10, carbon oxide nanotubes are replaced with carbon nanotubes. Compared with Example 3, the strength and thermal stability of Examples 8, 9, and 10 are somewhat reduced. This is because the composition and amount of acyl chloride modified carbon nanotubes have been adjusted. Too many or too few acyl chloride groups will affect the performance of carbon nanotubes. Too many acyl chloride groups will cause changes in the performance of carbon nanotubes and a decrease in performance, while too few will result in insufficient modification effect and limited performance improvement. Replacing carbon oxide nanotubes with carbon nanotubes reduces the active groups on the surface, resulting in a decrease in performance.

[0113] As shown in Tables 1 and 2, the only difference between Comparative Example 1 and Example 3 is that the coupling agent modified epoxy resin in Comparative Example 1 was replaced with bisphenol A type epoxy resin. Compared with Example 3, the strength and thermal stability of Comparative Example 1 decreased. This is because the lack of coupling agent modification treatment reduced the crosslinking degree and interfacial bonding force of the epoxy resin, thereby reducing the performance of the carbon fiber board.

[0114] As shown in Tables 1 and 2, the only difference between Comparative Example 2 and Example 3 is that the raw materials for preparing the polyimide prepolymer in Comparative Example 2 were replaced with 4,4'-diaminodiphenyl ether and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in a molar ratio of 1:1. Compared with Example 3, the strength and thermal stability of Comparative Example 2 decreased. This is because the lack of phenoxy groups resulted in a lack of regulation of the molecular chain of the polyimide prepolymer, which affected the microstructure and thus reduced the performance.

[0115] As can be seen from Tables 1 and 2, the only difference between Comparative Example 3 and Example 3 is that bismaleimide monomer is not added in Comparative Example 3. Compared with Example 3, the strength and thermal stability of Comparative Example 3 are reduced. This is because the lack of introduction of bismaleimide monomer weakens the bonding force between carbon fiber cloth and resin matrix, reduces heat resistance, and significantly reduces strength and thermal stability.

[0116] As shown in Tables 1 and 2, the only difference between Comparative Example 4 and Example 3 is that Comparative Example 4 replaces acyl chloride-modified carbon nanotubes with carbon nanotubes. Compared with Example 3, the strength and thermal stability of Comparative Example 4 are reduced. This is because carbon nanotubes lack acyl chloride modification, resulting in reduced dispersibility and reactivity, which reduces the improvement effect on the system and thus reduces the performance of the carbon fiber plate.

[0117] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A high-strength carbon fiber plate, characterized in that: The raw materials for preparation include carbon fiber cloth and slurry, wherein the slurry comprises the following components in parts by weight: 30-40 parts of coupling agent modified epoxy resin 20-30 parts of polyimide prepolymer 15-25 parts of bismaleimide monomer Acyl chloride modified carbon nanotubes 3-5 parts 8-12 parts of curing agent 5-10 parts diluent 1-2 parts antioxidant 1-2 parts of ultraviolet absorber; The raw materials for preparing the polyimide prepolymer include a composite diamine monomer and 3,3',4,4'-benzophenone tetracarboxylic dianhydride; The composite diamine monomer includes 4,4'-diaminodiphenyl ether and 1,3-bis(4-aminophenoxy)benzene; The molar ratio of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is (0.6-0.7):(0.3-0.4):

1.

2. The high-strength carbon fiber plate according to claim 1, characterized in that: The raw materials for preparing the coupling agent modified epoxy resin include bisphenol A type epoxy resin, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

3. The high-strength carbon fiber plate according to claim 2, characterized in that: The coupling agent-modified epoxy resin is prepared using the following steps: N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane were mixed and dispersed in ethanol and stirred to obtain a coupling agent solution. The coupling agent solution was added to bisphenol A type epoxy resin, heated and stirred to react, and the solvent was removed by rotary evaporation to obtain coupling agent modified epoxy resin.

4. The high-strength carbon fiber plate according to claim 1, characterized in that: The bismaleimide monomer includes 4,4'-bismaleimide diphenylmethane.

5. A high-strength carbon fiber plate according to claim 1, characterized in that: The raw materials for preparing the acyl chloride modified carbon nanotubes include carbon nanotube oxide and thionyl chloride.

6. A high-strength carbon fiber plate according to claim 5, characterized in that: The mass ratio of the carbon oxide nanotubes to thionyl chloride is 1:(0.6-0.8).

7. A processing method for high-strength carbon fiber plates as described in any one of claims 1-6, characterized in that: Includes the following steps: Carbon fiber cloth is impregnated into a slurry, and pressure is applied during the impregnation process to obtain a prepreg. The prepreg is heated and dried to obtain a pre-cured prepreg; the pre-cured prepreg is cut and placed into a mold for hot pressing; after cooling, it is demolded to obtain a high-strength carbon fiber sheet.

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