A high-temperature-resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures and a preparation method thereof

Abstract

The application relates to a high-temperature-resistant high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures and a preparation method thereof. The application relates to a high-performance polyimide adhesive and a preparation method thereof. The application solves the problems of narrow processing window, contradiction between flowability and heat resistance, and insufficient high-temperature aging resistance of the existing large-size curved honeycomb sandwich structure in bonding. The high-temperature-resistant high-strength adhesive is prepared from 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, m-aminophenylacetylene-terminated polyimide precursor resin, short-cut carbon fibers and solvent C; the preparation method comprises the following steps: one, preparing 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin; two, preparing m-aminophenylacetylene-terminated polyimide precursor resin; three, weighing; and four, preparing the adhesive. The application is used for the high-temperature-resistant high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures and a preparation method thereof.

Description

Technical Field

[0001] This invention relates to a high-performance polyimide adhesive and its preparation method. Background Technology

[0002] Honeycomb sandwich structures, due to their high specific strength and high specific stiffness, are often used as lightweight, high-load-bearing structural components and have been widely applied in fields such as aircraft and rail transportation. In recent years, with the increasing use of honeycomb sandwich structures in aircraft, high-speed rail, and other applications, the demand for honeycomb sandwich structures with characteristics such as large size, curved surfaces, and heterogeneous structures has been growing. However, large-curvature surfaces present challenges in flow control and high-temperature resistance during the adhesive bonding process. Therefore, there is an urgent need for an adhesive that combines good flowability, high-temperature bond strength, and resistance to high-temperature aging.

[0003] Polyimide (PI) possesses excellent temperature resistance, and polyimide adhesives can significantly improve this performance. However, traditional polyimide adhesives currently suffer from narrow processing windows and a trade-off between flowability and heat resistance, making them unsuitable for high-curvature honeycomb molding requirements. During bonding of high-curvature honeycombs, the adhesive often accumulates at the edges of curved surfaces due to uncontrolled flow, resulting in residual adhesive or localized adhesive gaps. Furthermore, these issues lead to inconsistent adhesive shrinkage during curing, causing stress concentration at the curved surface interface and reducing bond strength. If the viscosity of the polyimide adhesive is too low during high-temperature curing, excessive flowability can cause overflow; conversely, if the viscosity is too high, insufficient penetration can result in high residual adhesive content and uneven adhesive nodules on curved surfaces, ultimately failing to meet bonding requirements. Therefore, effectively controlling the viscosity of polyimide during high-temperature curing is a crucial method for improving its bonding performance.

[0004] Currently, phenylacetylene-based end-capping is commonly used to adjust the flowability and thermal stability of thermosetting polyimide adhesives. However, existing technologies for adhesives designed with a single end-cap have significant limitations. First, the processing window for a single end-cap design is narrow. For example, 4-phenylacetylene phthalic anhydride end-capping can increase high-temperature viscosity by increasing molecular chain rigidity, but this leads to excessively high viscosity in the initial processing stage (80℃~150℃), hindering the penetration of the adhesive into the honeycomb micropores, increasing residual adhesive content, and resulting in insufficient high-temperature curing. If low molecular weight molecular chains or end-capping agents are used to reduce the initial viscosity, the viscosity will be too low in the middle processing stage (150℃~250℃), easily causing overflow or uncontrolled glue nodules. The molecular structure of a single end-cap cannot meet the dual requirements of "high flow at low temperatures" and "high stability at high temperatures," leading to an imbalance between flowability and heat resistance in honeycomb bonding, especially when molding curved surfaces under load, which easily causes interfacial weakening problems.

[0005] To improve the viscosity and heat resistance of resins, inorganic fillers are often used. However, traditional fillers, such as glass fibers and inorganic particles, have poor compatibility with polyimide matrix resins, easily leading to phase separation or sedimentation and forming a weak interfacial layer. Furthermore, long fibers or high filler content can significantly increase viscosity, hindering the penetration of adhesives into the honeycomb micropores.

[0006] In summary, the core contradiction in the current bonding of large-size curved honeycomb sandwich structures lies in the fact that existing large-size curved honeycomb sandwich structures have narrow processing windows, contradictions between flowability and heat resistance, weakened phase separation interfaces of fillers, and insufficient high-temperature aging resistance. There is an urgent need to develop a polyimide adhesive that has both controllable flowability and high-temperature aging resistance, and to achieve efficient and low-cost manufacturing through process innovation. Summary of the Invention

[0007] This invention aims to address the problems of narrow processing window, contradiction between flowability and heat resistance, and insufficient high-temperature aging resistance in the bonding of existing large-size curved honeycomb sandwich structures. It provides a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures and its preparation method.

[0008] A high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts of chopped carbon fibers, and 100 to 200 parts of solvent C.

[0009] The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is prepared from 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A; the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95-0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06-0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1-10).

[0010] The repeating unit of polyamic acid in the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is:

[0011]

[0012] R1 is

[0013] R2 is

[0014] The m-aminophenylacetylene-terminated polyimide precursor resin is prepared from m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2-1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4-1); and the mass ratio of aromatic diamine B to solvent B is 1:(1-10).

[0015] The repeating unit of polyamic acid in the m-aminophenylacetylene-terminated polyimide precursor resin is:

[0016]

[0017] R3 is

[0018] R4 is

[0019] A method for preparing a high-temperature resistant, high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures, comprising the following steps:

[0020] I. Preparation of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin:

[0021] ① Weigh out 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A;

[0022] The molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95-0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06-0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1-10).

[0023] ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent A and aromatic diamine A are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride A is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then 4-phenylacetylene phthalic anhydride is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin.

[0024] II. Preparation of m-aminophenylacetylene-terminated polyimide precursor resin:

[0025] ① Weigh out m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B;

[0026] The molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2-1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4-1); and the mass ratio of aromatic diamine B to solvent B is 1:(1-10).

[0027] ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent B and aromatic diamine B are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride B is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then m-aminophenylacetylene is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain m-aminophenylacetylene-terminated polyimide precursor resin.

[0028] III. Weighing:

[0029] Weigh out 100 parts by weight of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts by weight of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts by weight of short-cut carbon fiber, and 100 to 200 parts by weight of solvent C.

[0030] IV. Preparation of Adhesives:

[0031] Under a nitrogen atmosphere, a reaction temperature of 50℃~60℃, and stirring conditions, weighed 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, m-aminophenylacetylene-terminated polyimide precursor resin, chopped carbon fibers, and solvent C are stirred for 2h~3h. Then, the reaction temperature is reduced from 50℃~60℃ to 25℃~30℃ to obtain a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures.

[0032] The beneficial effects of this invention are:

[0033] This invention achieves breakthroughs in high-temperature resistance and processing viscosity control of adhesives through molecular design and process innovation. Its beneficial effects and mechanisms of action are detailed below:

[0034] When using end-capping agents to increase molecular temperature resistance and adjust resin viscosity, the molecular structure of a single end-capping agent is insufficient to meet the dual requirements of temperature resistance and processing fluidity, thus limiting its application in the field of large curved honeycomb adhesives. This invention addresses this issue through multiple methods, including molecular structure adjustment, combination of long and short molecular chains, and inorganic doping. Firstly, molecular structure adjustment involves using two end-capping agents to end-cap polyimide precursor segments of different molecular weights. One is a long-chain polyimide precursor with a phenyl structure end-capped by 4-phenylacetylene phthalic anhydride, providing a certain viscosity at high temperatures to prevent excessively low viscosity from causing flow and overflow. The other is a short-chain polyimide precursor with an isomeric structure end-capped by m-aminophenylacetylene. This isomeric short-chain molecule acts as a lubricant, reducing resin viscosity and providing low viscosity during processing. This avoids difficulties in adhesive penetration into the honeycomb structure caused by excessively high viscosity, resulting in high residual adhesive content and uneven adhesive nodules on curved surfaces. Through the synergistic effect of the two end-capping agents, viscosity control of the adhesive during the processing stage is achieved.

[0035] By adjusting the molar ratio of diamine and dianhydride, the repeating units of the polyimide precursor molecular chain can be controlled, ultimately achieving the goal of regulating chain length, precursor molecular weight, viscosity, and the density of phenylacetylene groups. The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor is designed with a long-chain structure, with repeating units controlled in the range of 20–30 and a molecular weight of approximately 10,000–15,000. Due to the π-π stacking of the side phenyl groups and the entanglement of the long chains to form a physical cross-linking network, the final adhesive maintains a high viscosity (400 Pa·s–600 Pa·s) during the mid-processing stage (150–250 °C), effectively suppressing adhesive flow and overflow at high temperatures. Furthermore, the longer molecular chains effectively improve the toughness of the cured adhesive. The m-aminophenylacetylene-terminated polyimide precursor is designed with a short-chain structure, with repeating units controlled in the range of 2–5 and a molecular weight of approximately 1000–3000. Isomerization disrupts the symmetry of the molecular structure, and the low molecular weight design acts as a molecular lubricant, significantly reducing the viscosity (1000 Pa·s–3000 Pa·s) of the final adhesive solution during the initial processing stage (80℃–150℃). This lower processing viscosity ensures the adhesive wets the honeycomb surface, promotes penetration into the internal pores of the honeycomb, and improves the processability and heat resistance of the adhesive.

[0036] For long-chain segments capped with 4-phenylacetylene phthalic anhydride, rigid diamines (p-phenylenediamine, m-phenylenediamine, or 4,4-diaminobiphenyl) are preferred to increase the high-temperature heat resistance of the adhesive. Highly symmetric dianhydrides (3,3',4,4'-biphenyltetracarboxylic dianhydride or pyromellitic dianhydride) are preferred to improve molecular chain regularity and enhance high-temperature viscosity control. For short-chain segments capped with m-aminophenylacetylene, flexible diamines (4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenyl sulfone) and flexible dianhydrides (bisphenol A type diether dianhydride or 4,4'-oxobisphthalic anhydride) are preferred, using ether bonds or sulfonyl groups to enhance segment mobility. Based on the combined calculations of the proportions and molecular weights of the two end-capped polyimide precursor adhesives, the molar ratio of the two end-capping agents is 1:(0.5–0.8). During the mid-processing stage (150–200℃), this ensures that the long-chain segments provide appropriate viscosity, while the short-chain segments maintain fluidity through isomerization. This results in a smooth overall viscosity of the final adhesive (400 Pa·s–600 Pa·s). The adhesive climbs along the honeycomb wall under capillary action, forming uniform glue nodules that increase the bonding area, thereby enhancing the bonding effect and meeting the gel-setting requirements for honeycomb curved surface bonding. The mass fraction ratio of long chains to short chains is approximately 1:(0.5–1), which avoids both the decrease in heat resistance caused by excessive short chains and insufficient penetration caused by excessive long chains.

[0037] Regarding the inorganic doping interface, after acetone surface treatment, the sizing agent on the surface of the chopped carbon fibers is removed, leaving certain carboxyl and hydroxyl groups on the fiber surface. These groups form hydrogen bonds and π-π stacking interactions with the polyimide precursor, resulting in good compatibility with the adhesive and avoiding the phase separation problem of traditional inorganic fiber fillers. During the curing process, the carbon fibers can form three-dimensional thermally conductive pathways, effectively reducing the curing thermal stress of the adhesive and improving the overall fatigue resistance of the honeycomb structure.

[0038] In terms of temperature and aging resistance, the 4-phenylacetylene phthalic anhydride-terminated phenyl structure and chopped carbon fibers provide high heat resistance, while the m-aminophenylacetylene isomer structure inhibits interfacial hydrolysis during humid heat aging. The carbon fiber network further enhances the thermal conductivity of the adhesive, reduces curing thermal stress, and improves the overall temperature and aging resistance of the honeycomb structure. Through the synergistic innovation of dual-terminated agent molecular design and chopped fibers, the system systematically solves the problems of flow control failure and interfacial weakening of traditional polyimide adhesives in honeycomb bonding with large curvature. At the same time, it significantly improves high-temperature performance and processability, providing a reliable solution for the manufacturing of complex curved honeycomb sandwich structures in aerospace, rail transportation, and other fields. Attached Figure Description

[0039] Figure 1 The image shows the actual honeycomb structure after planar stretching at 200°C, which is bonded using the high-temperature and high-strength adhesive prepared in Example 1.

[0040] Figure 2This is a photograph of the aluminum honeycomb sandwich structure bonded using the high-temperature resistant and high-strength adhesive prepared in Example 2, after room temperature roller peeling.

[0041] Figure 3 The infrared spectrum of the high-temperature resistant and high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures, after curing:

[0042] Figure 4 Temperature-viscosity curve of the high-temperature resistant and high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures;

[0043] Figure 5 The high-temperature resistant and high-strength adhesive prepared for bonding large-size curved honeycomb sandwich structures in Example 1 is used to bond large-size curved honeycomb samples. (a) is a side view of the large-size honeycomb composite board sample, and (b) is a top view of the large-size honeycomb composite board sample.

[0044] Figure 6 Comparative images of high-temperature resistant and high-strength adhesives suitable for bonding large-size curved honeycomb sandwich structures prepared in Example 1 and Comparative Experiment 4, (a) is Example 1, (b) is Comparative Experiment 4;

[0045] Figure 7 The high-temperature resistant and high-strength adhesive prepared in Example 1 is used to bond a large-sized curved honeycomb sample cut into strips for a flat tensile test curve. Detailed Implementation

[0046] Specific Implementation Method 1: This embodiment provides a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures. It is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts of short-cut carbon fibers, and 100 to 200 parts of solvent C.

[0047] The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is prepared from 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A; the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95-0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06-0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1-10).

[0048] The repeating unit of polyamic acid in the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is:

[0049]

[0050] R1 is

[0051] R2 is

[0052] The m-aminophenylacetylene-terminated polyimide precursor resin is prepared from m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2-1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4-1); and the mass ratio of aromatic diamine B to solvent B is 1:(1-10).

[0053] The repeating unit of polyamic acid in the m-aminophenylacetylene-terminated polyimide precursor resin is:

[0054]

[0055] R3 is

[0056] R4 is

[0057] In this specific embodiment, a capping agent, an aromatic diamine, and an aromatic dianhydride are co-polymerized to form a capped polyimide precursor resin.

[0058] This specific embodiment achieves a balance between flow and adhesion properties in honeycomb high curvature molding through the synergistic design of dual end-capping agents and the doping of short-cut fibers.

[0059] The beneficial effects of this specific implementation method are:

[0060] This specific implementation method achieves breakthrough progress in high-temperature resistance and processing viscosity control of adhesives through molecular design and process innovation. Its beneficial effects and mechanisms of action are detailed below:

[0061] When using end-capping agents to increase molecular temperature resistance and adjust resin viscosity, the molecular structure of a single end-capping agent is insufficient to meet the dual requirements of temperature resistance and processing fluidity, thus limiting its application in the field of large curved honeycomb adhesives. This specific implementation method addresses this through multiple means: molecular structure adjustment, combination of long and short molecular chains, and inorganic doping. Firstly, molecular structure adjustment involves using two end-capping agents to end-cap polyimide precursor segments of different molecular weights. One is a long-chain polyimide precursor with a phenyl structure end-capped by 4-phenylacetylene phthalic anhydride, providing a certain viscosity for the adhesive at high temperatures and preventing excessively low viscosity from causing flow and overflow. The other is a short-chain polyimide precursor with an isomeric structure end-capped by m-aminophenylacetylene. The isomeric short-chain molecules act as a lubricant, reducing resin viscosity and providing low viscosity during processing. This avoids difficulties in adhesive penetration into the honeycomb structure caused by excessively high viscosity, resulting in high residual adhesive content and uneven adhesive nodules on curved surfaces. Through the synergistic effect of the two end-capping agents, viscosity control of the adhesive during the processing stage is achieved.

[0062] By adjusting the molar ratio of diamine and dianhydride, the repeating units of the polyimide precursor molecular chain can be controlled, ultimately achieving the goal of regulating chain length, precursor molecular weight, viscosity, and the density of phenylacetylene groups. The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor is designed with a long-chain structure, with repeating units controlled in the range of 20–30 and a molecular weight of approximately 10,000–15,000. Due to the π-π stacking of the side phenyl groups and the entanglement of the long chains to form a physical cross-linking network, the final adhesive maintains a high viscosity (400 Pa·s–600 Pa·s) during the mid-processing stage (150–250 °C), effectively suppressing adhesive flow and overflow at high temperatures. Furthermore, the longer molecular chains effectively improve the toughness of the cured adhesive. The m-aminophenylacetylene-terminated polyimide precursor is designed with a short-chain structure, with repeating units controlled in the range of 2–5 and a molecular weight of approximately 1000–3000. Isomerization disrupts the symmetry of the molecular structure, and the low molecular weight design acts as a molecular lubricant, significantly reducing the viscosity (1000 Pa·s–3000 Pa·s) of the final adhesive solution during the initial processing stage (80℃–150℃). This lower processing viscosity ensures the adhesive wets the honeycomb surface, promotes penetration into the internal pores of the honeycomb, and improves the processability and heat resistance of the adhesive.

[0063] For long-chain segments capped with 4-phenylacetylene phthalic anhydride, rigid diamines (p-phenylenediamine, m-phenylenediamine, or 4,4-diaminobiphenyl) are preferred to increase the high-temperature heat resistance of the adhesive. Highly symmetric dianhydrides (3,3',4,4'-biphenyltetracarboxylic dianhydride or pyromellitic dianhydride) are preferred to improve molecular chain regularity and enhance high-temperature viscosity control. For short-chain segments capped with m-aminophenylacetylene, flexible diamines (4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenyl sulfone) and flexible dianhydrides (bisphenol A type diether dianhydride or 4,4'-oxobisphthalic anhydride) are preferred, using ether bonds or sulfonyl groups to enhance segment mobility. Based on the combined calculations of the proportions and molecular weights of the two end-capped polyimide precursor adhesives, the molar ratio of the two end-capping agents is 1:(0.5–0.8). During the mid-processing stage (150–200℃), this ensures that the long-chain segments provide appropriate viscosity, while the short-chain segments maintain fluidity through isomerization. This results in a smooth overall viscosity of the final adhesive (400 Pa·s–600 Pa·s). The adhesive climbs along the honeycomb wall under capillary action, forming uniform glue nodules that increase the bonding area, thereby enhancing the bonding effect and meeting the gel-setting requirements for honeycomb curved surface bonding. The mass fraction ratio of long chains to short chains is approximately 1:(0.5–1), which avoids both the decrease in heat resistance caused by excessive short chains and insufficient penetration caused by excessive long chains.

[0064] Regarding the inorganic doping interface, after acetone surface treatment, the sizing agent on the surface of the chopped carbon fibers is removed, leaving certain carboxyl and hydroxyl groups on the fiber surface. These groups form hydrogen bonds and π-π stacking interactions with the polyimide precursor, resulting in good compatibility with the adhesive and avoiding the phase separation problem of traditional inorganic fiber fillers. During the curing process, the carbon fibers can form three-dimensional thermally conductive pathways, effectively reducing the curing thermal stress of the adhesive and improving the overall fatigue resistance of the honeycomb structure.

[0065] In terms of temperature and aging resistance, the 4-phenylacetylene phthalic anhydride-terminated phenyl structure and chopped carbon fibers provide high heat resistance, while the m-aminophenylacetylene isomer structure inhibits interfacial hydrolysis during humid heat aging. The carbon fiber network further enhances the thermal conductivity of the adhesive, reduces curing thermal stress, and improves the overall temperature and aging resistance of the honeycomb structure. Through the synergistic innovation of dual-terminated agent molecular design and chopped fibers, the system systematically solves the problems of flow control failure and interfacial weakening of traditional polyimide adhesives in honeycomb bonding with large curvature. At the same time, it significantly improves high-temperature performance and processability, providing a reliable solution for the manufacturing of complex curved honeycomb sandwich structures in aerospace, rail transportation, and other fields.

[0066] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the length of the chopped carbon fibers is one or a combination of 3mm, 4mm, and 5mm; the chopped carbon fibers are pretreated chopped carbon fibers, and the pretreatment process is carried out according to the following steps: placing the carbon fibers in an acetone solution, heating in a water bath at a temperature of 45℃~55℃ for 10h~14h, then washing multiple times with deionized water, and finally drying at a temperature of 55℃~65℃ for 6h~10h. Everything else is the same as in Specific Implementation Method One.

[0067] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that solvents A, B, and C are all N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone. Everything else is the same as in Specific Implementation Method One or Two.

[0068] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the aromatic diamine A is p-phenylenediamine, m-phenylenediamine, or 4,4-diaminobiphenyl. Everything else is the same as in Specific Implementation Methods One to Three.

[0069] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the aromatic dianhydride A is 3,3',4,4'-biphenyltetracarboxylic dianhydride or pyromellitic dianhydride. Everything else is the same as in Specific Implementation Methods One to Four.

[0070] Specific Embodiment Six: This embodiment differs from Specific Embodiments One to Five in that the aromatic diamine B is 4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenyl sulfone. Everything else is the same as in Specific Embodiments One to Five.

[0071] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the aromatic dianhydride B is a bisphenol A type diether dianhydride or 4,4'-oxybisphthalic anhydride. Everything else is the same as in Specific Implementation Methods One to Six.

[0072] Specific Implementation Method Eight: This implementation method provides a method for preparing a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures. It is carried out according to the following steps:

[0073] I. Preparation of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin:

[0074] ① Weigh out 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A;

[0075] The molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95-0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06-0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1-10).

[0076] ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent A and aromatic diamine A are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride A is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then 4-phenylacetylene phthalic anhydride is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin.

[0077] II. Preparation of m-aminophenylacetylene-terminated polyimide precursor resin:

[0078] ① Weigh out m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B;

[0079] The molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2-1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4-1); and the mass ratio of aromatic diamine B to solvent B is 1:(1-10).

[0080] ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent B and aromatic diamine B are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride B is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then m-aminophenylacetylene is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain m-aminophenylacetylene-terminated polyimide precursor resin.

[0081] III. Weighing:

[0082] Weigh out 100 parts by weight of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts by weight of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts by weight of short-cut carbon fiber, and 100 to 200 parts by weight of solvent C.

[0083] IV. Preparation of Adhesives:

[0084] Under a nitrogen atmosphere, a reaction temperature of 50℃~60℃, and stirring conditions, weighed 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, m-aminophenylacetylene-terminated polyimide precursor resin, chopped carbon fibers, and solvent C are stirred for 2h~3h. Then, the reaction temperature is reduced from 50℃~60℃ to 25℃~30℃ to obtain a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures.

[0085] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the stirring speed described in Step One ②, Step Two ②, and Step Four is 100 rpm to 200 rpm. Everything else is the same as in Specific Implementation Method Eight.

[0086] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Eight or Nine in that: in step one ②, aromatic dianhydride A is added to the reaction system in three equal portions; in step two ②, aromatic dianhydride B is added to the reaction system in three equal portions. Everything else is the same as in Specific Implementation Method Eight or Nine.

[0087] The beneficial effects of the present invention are verified using the following embodiments:

[0088] Example 1:

[0089] A high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 parts of m-aminophenylacetylene-terminated polyimide precursor resin, 2 parts of short-cut carbon fiber and 100 parts of solvent C.

[0090] The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is prepared from 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A; the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:0.95; the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:0.1; and the mass ratio of aromatic diamine A to solvent A is 1:10.

[0091] The repeating unit of polyamic acid in the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is:

[0092]

[0093] R1 is

[0094] R2 is

[0095] The m-aminophenylacetylene-terminated polyimide precursor resin is prepared from m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:1.2; the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:0.4; and the mass ratio of aromatic diamine B to solvent B is 1:10.

[0096] The repeating unit of polyamic acid in the m-aminophenylacetylene-terminated polyimide precursor resin is:

[0097]

[0098] R3 is

[0099] R4 is

[0100] The length of the chopped carbon fiber is 3mm (Jiangsu Hengshen HF40); the chopped carbon fiber is pretreated chopped carbon fiber, and the pretreatment process is carried out according to the following steps: the carbon fiber is placed in an acetone solution, heated in a water bath at a temperature of 50℃ for 12 hours, then washed three times with deionized water, and finally dried at a temperature of 60℃ for 8 hours.

[0101] Solvents A, B, and C are all N,N-dimethylformamide.

[0102] The aromatic diamine A is p-phenylenediamine.

[0103] The aromatic dianhydride A is 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0104] The aromatic diamine B is 4,4'-diaminodiphenyl ether.

[0105] The aromatic dianhydride B is a bisphenol A type diether dianhydride.

[0106] A method for preparing a high-temperature resistant, high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures, comprising the following steps:

[0107] I. Preparation of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin:

[0108] ① Weigh out 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A;

[0109] ② Under a nitrogen atmosphere, at a temperature of 40℃ and a stirring speed of 150rpm, solvent A and aromatic diamine A were stirred and dissolved for 3h. Then the reaction temperature was raised to 60℃, and aromatic dianhydride A was added to the reaction system in three equal portions. Under a nitrogen atmosphere, at a temperature of 60℃ and a stirring speed of 150rpm, the reaction was stirred for 3h. Then 4-phenylacetylene phthalic anhydride was added, and under a nitrogen atmosphere, at a temperature of 60℃ and a stirring speed of 150rpm, the reaction was stirred for 4h to obtain 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin.

[0110] II. Preparation of m-aminophenylacetylene-terminated polyimide precursor resin:

[0111] ① Weigh out m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B;

[0112] ② Under a nitrogen atmosphere, at a temperature of 40℃ and a stirring speed of 150 rpm, solvent B and aromatic diamine B were stirred and dissolved for 3 hours. Then the reaction temperature was raised to 60℃, and aromatic dianhydride B was added to the reaction system in three equal portions. Under a nitrogen atmosphere, at a temperature of 60℃ and a stirring speed of 150 rpm, the reaction was stirred for 3 hours. Then m-aminophenylacetylene was added, and under a nitrogen atmosphere, at a temperature of 60℃ and a stirring speed of 150 rpm, the reaction was stirred for 4 hours to obtain m-aminophenylacetylene-terminated polyimide precursor resin.

[0113] III. Weighing:

[0114] Weigh out 100 parts by weight of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 parts by weight of m-aminophenylacetylene-terminated polyimide precursor resin, 2 parts by weight of short-cut carbon fiber and 100 parts by weight of solvent C.

[0115] IV. Preparation of Adhesives:

[0116] Under nitrogen atmosphere, reaction temperature of 60℃ and stirring speed of 150 rpm, weighed 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, m-aminophenylacetylene-terminated polyimide precursor resin, chopped carbon fibers and solvent C were stirred for 2 h. Then the reaction temperature was reduced from 60℃ to 25℃ to obtain a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures.

[0117] Example 2: This example differs from Example 1 in that: the aromatic diamine A is 4,4-diaminobiphenyl; the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:0.96; the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:0.08; the amount of the m-aminophenylacetylene-terminated polyimide precursor resin is 80 parts; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:1.3; the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:0.6; the amount of solvent C is 150 parts; and solvents A, B, and C are all N-methylpyrrolidone. Everything else is the same as in Example 1.

[0118] Example 3: This example differs from Example 1 in that: the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:0.96; the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:0.06; the amount of the m-aminophenylacetylene-terminated polyimide precursor resin is 80 parts; the aromatic diamine B is 4,4'-diaminodiphenyl sulfone; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:1.3; the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:0.6; the amount of solvent C is 150 parts; and solvents A, B, and C are all N-methylpyrrolidone. Everything else is the same as in Example 1.

[0119] Example 4: This example differs from Example 1 in that: the m-aminophenylacetylene-terminated polyimide precursor resin is 90 parts; the chopped carbon fiber is 3 parts; the chopped carbon fiber consists of 1 part of carbon fiber with a length of 3 mm and 2 parts of carbon fiber with a length of 5 mm by mass; and the solvent C is 200 parts. Everything else is the same as in Example 1.

[0120] Example 5: This example differs from Example 1 in that: the amount of the m-aminophenylacetylene-terminated polyimide precursor resin is 60 parts; the amount of solvent C is 120 parts; and solvents A, B, and C are all N-methylpyrrolidone. Everything else is the same as in Example 1.

[0121] Example 6: This example differs from Example 1 in that: the amount of the m-aminophenylacetylene-terminated polyimide precursor resin is 100 parts; the aromatic diamine B is 4,4'-diaminodiphenyl sulfone; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:1.5; the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:0.6; the amount of solvent C is 160 parts; and solvents A, B, and C are all N-methylpyrrolidone. Everything else is the same as in Example 1.

[0122] Example 7: This example differs from Example 1 in that: the aromatic diamine A is 4,4-diaminobiphenyl; the aromatic dianhydride A is pyromellitic dianhydride; and the amount of diced carbon fiber is 1.5 parts. Everything else is the same as in Example 1.

[0123] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the m-aminophenylacetylene-terminated polyimide precursor resin and chopped carbon fibers are omitted; the high-temperature resistant and high-strength adhesive is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin and 100 parts of solvent C. Everything else is the same as in Example 1.

[0124] Comparative Experiment 2: This comparative experiment differs from Example 1 in that the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin and chopped carbon fibers are omitted; the high-temperature resistant and high-strength adhesive is prepared by weight of 80 parts of m-aminophenylacetylene-terminated polyimide precursor resin and 100 parts of solvent C. Everything else is the same as in Example 1.

[0125] Comparative Experiment 3: This comparative experiment differs from Example 1 in that: short-cut carbon fibers are omitted; the high-temperature resistant and high-strength adhesive is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 parts of m-aminophenylacetylene-terminated polyimide precursor resin, and 100 parts of solvent C. Everything else is the same as in Example 1.

[0126] Comparative Experiment 4: This comparative experiment differs from Example 1 in that the high-temperature resistant, high-strength adhesive was prepared by weight from 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 150 parts of m-aminophenylacetylene-terminated polyimide precursor resin, 2 parts of chopped carbon fibers, and 100 parts of solvent C. Everything else was the same as in Example 1.

[0127] (1) The adhesives prepared in Examples 1 to 7 and Comparative Experiments 1 to 4 were placed between honeycomb (aramid paper honeycomb, aluminum honeycomb, polyimide honeycomb) and stainless steel panels (316L stainless steel from Wuxi Date Stainless Steel Co., Ltd.) for bonding, with a bonding size of 10cm × 10cm; the aramid paper honeycomb was from Taihe New Materials Co., Ltd. The model and aluminum honeycomb are from Hexcel. Model III, polyimide honeycomb material, is manufactured by Jiangsu Xiannuo New Materials Co., Ltd. Model; The curing process is as follows: first, heating at 80℃ and 0.2MPa for 1 hour; then heating at 180℃ and 0.2MPa for 1 hour; then heating at 300℃ and 0.2MPa for 2 hours; finally heating at 370℃ and 0.1MPa for 1 hour to obtain the honeycomb sandwich structure. Various performance tests are then performed on it, and the test conditions refer to the following standards (methods):

[0128] 1. Glue Climbing Height Measurement: Use vernier calipers to measure the distance between the highest point of the glue climb and the edge of the honeycomb at the bonding point between the honeycomb and the board.

[0129] 2. Planar tensile test: The planar tensile test method for honeycomb sandwich structures is adopted according to GJB 130.4-1986; the planar tensile test at 200℃ is a planar tensile test of honeycomb sandwich structures under the condition that the ambient temperature is set to 200℃.

[0130] 3. Peel strength: Tested according to GJB130.7-1986 Roller peel test method for bonded aluminum honeycomb sandwich structures.

[0131] 4. Shear strength: The shear strength of the adhesive honeycomb was determined according to GJB1874-94. The room temperature shear strength after damp heat aging was specifically tested in the following steps: 85℃ 85%RH was used to test the honeycomb sandwich structure under the conditions of 85℃ and 85% humidity, with aging times of 168h and 1000h respectively, and then the room temperature shear strength was tested.

[0132] 5. Honeycomb water absorption rate: Place the cured honeycomb sandwich structure in an environment of 25℃ and 100% humidity for 100 hours, and weigh the honeycomb sandwich structure before and after placement. Honeycomb water absorption rate = (weight after water absorption - weight before water absorption) / weight before water absorption × 100%; Honeycomb water absorption rate: Place the cured honeycomb sandwich structure in a water bath, with water covering the honeycomb sandwich structure, and boil it at 80℃ for 2 hours. Wipe off the surface moisture of the honeycomb after boiling, and place it in an oven at 60℃ for 8 hours. Honeycomb water absorption rate = (weight after boiling and drying - weight before boiling) / weight before boiling × 100%.

[0133] 6. The bonding effect with the honeycomb interlayer is determined by visual inspection. Damaged or detached surfaces are observed. Honeycomb damage is considered honeycomb failure; no adhesive residue indicates interface debonding; adhesive residue indicates adhesive layer damage; and bonding failure is considered detachment.

[0134] (2) Adhesive test:

[0135] 1. Molecular weight test: The number-average molecular weight (Mn) of the polyimide precursor resin with phenylacetylene phthalic anhydride end-capped prepared in step one of Example 1 and the polyimide precursor resin with m-aminophenylacetylene end-capped prepared in step two was tested using a FEI Sirion200 chromatographic analyzer. The mobile phase was chromatographic grade tetrahydrofuran, and polystyrene was used as an internal standard. The sample was placed in an 80°C oven for 6 hours to remove the solvent, and then dissolved in chromatographic grade tetrahydrofuran.

[0136] 2. Infrared test: The high-temperature resistant and high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures, was cured and then the infrared spectrum was tested; Curing process: The adhesive was placed in an oven and heated at 80°C for 1 hour, 180°C for 1 hour, 300°C for 2 hours, and 370°C for 1 hour to complete the curing process.

[0137] (3) Bonding large-size curved honeycomb surfaces:

[0138] The adhesives prepared in Examples 1 to 7 and Comparative Experiments 1 to 4 were used to bond large-size curved polyimide honeycomb and polyimide composite boards. The bonding size was 45cm × 12cm, with a large curvature (10cm < radius of curvature < ∞) curved honeycomb. The polyimide honeycomb was manufactured by Jiangsu Xiannuo New Materials Co., Ltd. The model is a polyimide composite board, which is self-made (glass cloth is impregnated in a polyimide precursor solution, taken out and dried to obtain prepreg, and three layers of prepreg are placed in an autoclave for curing to obtain a polyimide composite board, wherein the polyimide precursor solution is prepared from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA)). The curing process for the composite board and honeycomb bonding is as follows: first, heating at 80℃ and 0.2MPa for 1 hour, then heating at 180℃ and 0.2MPa for 1 hour, then heating at 300℃ and 0.2MPa for 2 hours, and finally heating at 370℃ and 0.1MPa for 1 hour to obtain a polyimide composite board / large-size curved honeycomb bonding component.

[0139] The large curved honeycomb was cut into 2.5×10cm strips and then relevant tests were conducted.

[0140] 1. Peel strength: Tested according to GJB130.7-1986 Roller peel test method for bonded aluminum honeycomb sandwich structures.

[0141] 2. Planar tensile test: The planar tensile test method for honeycomb sandwich structures is adopted according to GJB 130.4-1986.

[0142] Table 1

[0143]

[0144]

[0145]

[0146] Table 2

[0147]

[0148] Table 3

[0149]

[0150]

[0151] Figure 1 The image shows the actual honeycomb structure of the aluminum honeycomb sandwich structure bonded using the high-temperature resistant and high-strength adhesive prepared in Example 1 after planar stretching at 200°C. As can be seen from the image, the adhesive from Example 1 can form good adhesive nodules as it climbs along the honeycomb.

[0152] Figure 2 This is a photograph of the aluminum honeycomb sandwich structure bonded using the high-temperature resistant and high-strength adhesive prepared in Example 2, after room temperature roller peeling. (Comparison) Figure 1 It can be seen that the viscosity of Example 2 is lower than that of Example 1, which can form glue nodules, but the height of the adhesive climbing along the honeycomb is reduced.

[0153] Figure 3 The infrared spectrum of the high-temperature resistant and high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures, after curing: As shown in the figure, from 1780 cm⁻¹... -1 and 1720cm -1 The presence of a carbonyl symmetric absorption peak indicates that iminolation is complete.

[0154] Figure 4 The temperature-viscosity curves of the high-temperature resistant, high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures, are shown in the figure. As can be seen, the high-temperature resistant, high-strength adhesive for bonding large-size curved honeycomb sandwich structures has a low viscosity (1000 Pa·s to 3000 Pa·s) in the initial processing stage (80℃ to 140℃), which is beneficial for the penetration of the adhesive into the internal pores of the honeycomb. In the middle processing stage (150℃ to 250℃), the final adhesive maintains a high viscosity (400 Pa·s to 600 Pa·s), effectively suppressing the flow and overflow of the adhesive at high temperatures.

[0155] Figure 5 The high-temperature resistant, high-strength adhesive prepared in Example 1, suitable for bonding large-size curved honeycomb sandwich structures, is used to bond large-size curved honeycomb samples. (a) is a side view of the large-size honeycomb composite board sample, and (b) is a top view of the large-size honeycomb composite board sample. As shown in the figures, there is no adhesive overflow after bonding the large-size curved honeycomb with the high-temperature resistant, high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures.

[0156] Figure 6The figures show comparisons of the high-temperature resistant, high-strength adhesives used in Example 1 and Comparative Experiment 4 for bonding large-sized curved honeycomb sandwich structures. (a) is Example 1, and (b) is Comparative Experiment 4. As can be seen from the figures, the high-temperature resistant, high-strength adhesives used in Example 1 showed no adhesive overflow after bonding the large-sized curved honeycomb structure. However, in Comparative Experiment 4, due to the excessive proportion of m-aminophenylacetylene, the viscosity decreased, resulting in significant adhesive overflow.

[0157] Figure 7 The figure shows the tensile test curves after the large-size curved honeycomb sample, prepared in Example 1 and suitable for bonding large-size curved honeycomb sandwich structures, was cut into strips. As can be seen from the figure, the high-temperature resistant and high-strength adhesive used for bonding large-size curved honeycomb sandwich structures achieved a maximum planar tensile strength of 8.4 MPa, indicating a very high bonding strength.

Claims

1. A high-temperature resistant, high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures, characterized in that... It is prepared by weight of 100 parts of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts of short-cut carbon fibers and 100 to 200 parts of solvent C. The 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is prepared from 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A; the molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95~0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06~0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1~10). The structural formula of the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is as follows: ； R1 is or ; R2 is , or ; The molecular weight of the 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin is 10,000 to 15,000. The m-aminophenylacetylene-terminated polyimide precursor resin is prepared from m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B; the molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2~1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4~1); and the mass ratio of aromatic diamine B to solvent B is 1:(1~10). The structural formula of the m-aminophenylacetylene-terminated polyimide precursor resin is as follows: ； R3 is or ; R4 is or ; The molecular weight of the m-aminophenylacetylene-terminated polyimide precursor resin is 1000~3000.

2. The high-temperature resistant and high-strength adhesive for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... The length of the chopped carbon fiber is one or a combination of 3mm, 4mm and 5mm; the chopped carbon fiber is pretreated chopped carbon fiber, and the pretreatment process is carried out according to the following steps: the carbon fiber is placed in an acetone solution and heated in a water bath at a temperature of 45℃~55℃ for 10h~14h, then washed multiple times with deionized water, and finally dried at a temperature of 55℃~65℃ for 6h~10h.

3. The high-temperature resistant and high-strength adhesive for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... Solvent A, solvent B and solvent C are all N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone.

4. The high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... The aromatic diamine A is p-phenylenediamine, m-phenylenediamine, or 4,4-diaminobiphenyl.

5. The high-temperature resistant and high-strength adhesive for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... The aromatic dianhydride A is 3,3',4,4'-biphenyltetracarboxylic dianhydride or pyromellitic dianhydride.

6. The high-temperature resistant and high-strength adhesive for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... The aromatic diamine B is 4,4'-diaminodiphenyl ether or 4,4'-diaminodiphenyl sulfone.

7. The high-temperature resistant and high-strength adhesive for bonding large-size curved honeycomb sandwich structures according to claim 1, characterized in that... The aromatic dianhydride B is a bisphenol A type diether dianhydride or a 4,4'-oxobisphthalic anhydride.

8. A method for preparing a high-temperature resistant, high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures as described in claim 1, characterized in that... It is done in the following steps: I. Preparation of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin: ① Weigh out 4-phenylacetylene phthalic anhydride, aromatic diamine A, aromatic dianhydride A, and solvent A; The molar ratio of aromatic diamine A to aromatic dianhydride A is 1:(0.95~0.97); the molar ratio of aromatic diamine A to 4-phenylacetylene phthalic anhydride is 1:(0.06~0.1); and the mass ratio of aromatic diamine A to solvent A is 1:(1~10). ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent A and aromatic diamine A are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride A is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then 4-phenylacetylene phthalic anhydride is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin. II. Preparation of m-aminophenylacetylene-terminated polyimide precursor resin: ① Weigh out m-aminophenylacetylene, aromatic diamine B, aromatic dianhydride B, and solvent B; The molar ratio of aromatic diamine B to aromatic dianhydride B is 1:(1.2~1.5); the molar ratio of aromatic diamine B to m-aminophenylacetylene is 1:(0.4~1); the mass ratio of aromatic diamine B to solvent B is 1:(1~10). ② Under a nitrogen atmosphere, at a temperature of 40℃~48℃ and with stirring, solvent B and aromatic diamine B are stirred and dissolved for 1h~5h. Then the reaction temperature is raised to 50℃~60℃, and aromatic dianhydride B is added to the reaction system. Under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 3h~5h. Then m-aminophenylacetylene is added, and under a nitrogen atmosphere, at a temperature of 50℃~60℃ and with stirring, the reaction is stirred for 2h~4h to obtain m-aminophenylacetylene-terminated polyimide precursor resin. III. Weighing: Weigh out 100 parts by weight of 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, 50 to 100 parts by weight of m-aminophenylacetylene-terminated polyimide precursor resin, 0.1 to 5 parts by weight of short-cut carbon fiber, and 100 to 200 parts by weight of solvent C. IV. Preparation of Adhesives: Under a nitrogen atmosphere, a reaction temperature of 50℃~60℃, and stirring conditions, weighed 4-phenylacetylene phthalic anhydride-terminated polyimide precursor resin, m-aminophenylacetylene-terminated polyimide precursor resin, chopped carbon fibers, and solvent C are stirred for 2h~3h. Then, the reaction temperature is reduced from 50℃~60℃ to 25℃~30℃ to obtain a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures.

9. A method for preparing a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures according to claim 8, characterized in that... The stirring speed described in Step 1②, Step 2② and Step 4 is 100rpm~200rpm.

10. A method for preparing a high-temperature resistant and high-strength adhesive suitable for bonding large-size curved honeycomb sandwich structures according to claim 8, characterized in that... Step 1②: Add aromatic dianhydride A to the reaction system in three equal portions; Step 2②: Add aromatic dianhydride B to the reaction system in three equal portions.

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