Tear-resistant and high-temperature-resistant film material and preparation method thereof

Abstract

The invention belongs to the technical field of polyimide film materials, and discloses a tear-resistant high-temperature-resistant film material and a preparation method thereof. The method comprises the following steps: firstly preparing a diamine monomer containing a biimidazole structure, then carrying out a chain extension cross-linking reaction on the diamine monomer and a polyamide acid prepolymer to construct a three-dimensional cross-linked network, and finally carrying out an imidization reaction and post-treatment to obtain the thin film material. In the molecular structure of the film, a biimidazole structural unit is connected with a polyimide main chain through a chemical bond to form a cross-linked network, nitrogen atoms on an imidazole ring of the biimidazole structural unit and groups such as carbonyl of the main chain form hydrogen bond interaction, and the biimidazole structural unit is used as a sacrifice bond to preferentially break to dissipate energy when being stressed, so that crack propagation is effectively prevented. The material has the advantages of high temperature resistance, high strength, high toughness and excellent tear resistance, and can meet the requirements of harsh fields such as flexible display, aerospace high-temperature sealing and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of polyimide film materials. More specifically, this invention relates to a tear-resistant and high-temperature resistant film material and its preparation method. This film material is particularly suitable for fields with stringent requirements for heat resistance and mechanical properties, such as flexible electronic devices, aerospace high-temperature sealing, and flexible display substrates. Background Technology

[0002] With the rapid development of flexible electronic devices, aerospace equipment, and next-generation display technologies, the demand for high-performance polymer thin film materials is becoming increasingly urgent. Especially in applications such as flexible display substrates, high-temperature fuel pump seals for aircraft engines, and flexible copper-clad laminates, thin film materials are required to not only possess excellent high-temperature resistance (long-term operating temperature >300℃, low coefficient of thermal expansion), but also outstanding mechanical strength, tear resistance, and folding resistance.

[0003] Polyimide (PI), as a high-performance polymer, has been widely used in the aforementioned fields due to its excellent thermal stability, mechanical properties, and electrical insulation properties. For example, commercial polyimide films such as DuPont's Kapton series and Ube Industries' Upilex series are currently among the high-performance polymer materials with excellent overall performance on the market. However, with the continuous expansion of application scenarios and the increasing performance requirements, these traditional polyimide materials have gradually shown limitations in some aspects: First, there is still room for improvement in thermal properties, especially the high coefficient of thermal expansion, which limits its application as a high-precision substrate; second, insufficient tear resistance and toughness, making it prone to catastrophic failure when subjected to complex stress or minor damage; third, although most methods of reinforcing polyimide with inorganic nanofillers (such as graphene and carbon nanotubes) can improve strength, they often come at the cost of sacrificing ductility and toughness.

[0004] In recent years, researchers have attempted to improve the heat resistance and mechanical properties of polyimides simultaneously through molecular structure design. For example, patent CN120059183A introduces rigid heterocyclic structures (such as imidazole and oxazole) into the main chain, which can increase the rigidity and linearity of the molecular chain, thus reducing the coefficient of thermal expansion and improving thermal stability. However, this approach uses a linear copolymer structure, which, although introducing rigid units and hydrogen bonds, lacks an effective three-dimensional cross-linking network. Under complex stress or minor damage, cracks easily propagate along the molecular chains, and the tear resistance and toughness need further improvement. As flexible electronic devices develop towards ultrathinness and foldability, higher requirements are placed on the tear resistance of thin film materials, which existing linear polyimide materials struggle to meet.

[0005] How to organically combine these molecular design concepts to develop a polyimide film material that combines ultra-high heat resistance, excellent tear resistance and good processability remains a technical challenge that needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a tear-resistant and high-temperature resistant thin film material and its preparation method. The tear-resistant and high-temperature resistant thin film material provided by this invention has high temperature resistance, high strength, high toughness and excellent tear resistance, which can meet the harsh requirements of flexible display, aerospace and other fields.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a tear-resistant and high-temperature resistant thin film material, comprising the following steps: (1) Preparation of diamine monomers containing a diimidazole structure (BID): Aromatic aminobenzoic acid derivatives and aromatic diamine compounds are used as raw materials to carry out cyclization reaction in an acidic dehydration medium to obtain diamine monomers containing a diimidazole structure. (2) Preparation of polyamic acid prepolymer solution: Dissolve aromatic diamine monomer in a polar aprotic solvent, stir to dissolve, add aromatic dianhydride monomer, and carry out polymerization reaction under low temperature conditions to obtain polyamic acid prepolymer solution; (3) Crosslinking modification reaction: The diamine monomer containing the bisimidazole structure obtained in step (1) is mixed with the polyamic acid prepolymer solution obtained in step (2) and a chain extension crosslinking reaction is carried out to obtain the modified polyamic acid prepolymer. (4) Imidification reaction: The modified polyamic acid prepolymer obtained in step (3) is mixed with a dehydrating agent and subjected to an imidization reaction. After post-treatment, a tear-resistant and high-temperature resistant polyimide film material is obtained.

[0008] Preferably, in step (1), the method for preparing the diamine monomer containing the diimidazole structure includes: adding an acidic dehydration medium into a reactor and heating and stirring until clear; sequentially adding an aromatic diamine compound and an aromatic aminobenzoic acid derivative, and gradually increasing the temperature to carry out a cyclization reaction; after the reaction is completed, slowly pouring the reaction solution into a precipitant to precipitate a solid product; after washing, neutralizing, and drying, a crude product is obtained; the crude product is purified by recrystallization with an organic solvent, and after filtration and drying, a purified diamine monomer containing the diimidazole structure is obtained.

[0009] Preferably, the acidic dehydration medium is a mixture of polyphosphoric acid and phosphorus pentoxide, wherein the mass ratio of polyphosphoric acid to phosphorus pentoxide is 100:5-30; the aromatic diamine compound is one or more of 3,3'-diaminobiphenyl, 4,4'-diaminobiphenyl, and 3,4'-diaminobiphenyl; the aromatic aminobenzoic acid derivative is one or more of p-aminobenzoic acid, m-aminobenzoic acid, and o-aminobenzoic acid; the precipitant is one or more of deionized water, methanol, and ethanol; and the organic solvent is one or more of anhydrous ethanol, methanol, and acetone.

[0010] Preferably, in step (1), the specific process conditions for the cyclization reaction are: reaction temperature 160-220℃, reaction time 12-30h; the total mass ratio of the acidic dehydration medium to the reaction raw materials is 5-15:1; and the molar ratio of the aromatic diamine compound to the aromatic aminobenzoic acid derivative is 1:1.8-2.2.

[0011] Preferably, in step (2), the aromatic diamine monomer is one or more of 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 3,3'-diaminodiphenyl ether; the aromatic dianhydride monomer is one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride; the molar ratio of the aromatic diamine monomer to the aromatic dianhydride monomer is 1:1.00 to 1.06; the polar aprotic solvent is any one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; the solid content of the polyamic acid prepolymer solution is 8 to 25 wt%; the polymerization reaction temperature is -5 to 15°C, and the reaction time is 3 to 10 h.

[0012] Preferably, in step (3), the amount of diamine monomer containing the diimidazole structure added is 2 to 25 mol of the aromatic diamine monomer; the chain extension and crosslinking reaction temperature is 30 to 70°C, and the reaction time is 10 to 48 h.

[0013] Preferably, in step (4), the dehydrating agent is a mixture of acetic anhydride and tertiary amine compounds, and the molar ratio of acetic anhydride to tertiary amine compounds is 1:0.8 to 1.2; the tertiary amine compounds are one or more of triethylamine, pyridine, and N,N-dimethylaniline; the amount of dehydrating agent added is based on a molar ratio of aromatic dianhydride monomer to dehydrating agent of 1:4 to 12; the chemical imidization reaction temperature is 20 to 50°C, and the reaction time is 8 to 30 h.

[0014] Preferably, step (4) is followed by a post-processing step: the imidization reaction system is poured into a precipitant to precipitate a solid polymer; the solid is collected by filtration, washed 2 to 5 times with a detergent, and dried to obtain a polyimide resin; the polyimide resin is dissolved in a polar aprotic solvent to prepare a casting solution, which is then cast, evaporated, and heat-treated to obtain a tear-resistant and high-temperature resistant thin film material; the thickness of the thin film material is 10 to 60 μm.

[0015] This invention also provides a tear-resistant and high-temperature resistant thin film material, prepared by the above-described method. Its molecular structure contains rigid bisimidazole heterocyclic structural units, and these bisimidazole structural units are chemically bonded to the polyimide backbone to form a cross-linked network structure. The thin film material has a glass transition temperature ≥400℃, a 5% thermal decomposition temperature ≥550℃, a coefficient of thermal expansion ≤12ppm / K, a tensile strength ≥170MPa, an elongation at break ≥8%, and a fracture energy ≥140kJ / m². 2 .

[0016] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a tear-resistant and high-temperature resistant thin film material. By performing a chain extension and crosslinking reaction between a rigid diamine monomer (BID) containing a bisimidazole structure and a polyamic acid prepolymer, a three-dimensional chemical crosslinking network is successfully constructed within a polyimide matrix. Compared to simple linear polyimides in the prior art (such as Comparative Example 1), the crosslinking network structure of this invention can more effectively transfer and disperse applied stress, avoiding stress concentration at the molecular chain ends, thereby significantly improving the overall mechanical strength and structural stability of the material.

[0017] This invention is the first to organically combine a rigid bisimidazole structure with a dynamic hydrogen bond network. The nitrogen atom on the imidazole ring acts as a hydrogen bond acceptor, forming abundant intermolecular and intramolecular hydrogen bonds with hydrogen bond donors such as carbonyl and imine groups on the polyimide backbone. When the material is subjected to external impact or has minor defects, these hydrogen bonds preferentially break as "sacrificial bonds," absorbing a large amount of energy, effectively passivating the crack tip, and preventing crack initiation and propagation.

[0018] Unlike highly cross-linked thermosetting polyimides, this invention employs a two-step process: first, chemically imidizing to obtain a soluble resin, then casting into a film followed by heat treatment. The resulting polyimide resin exhibits excellent solubility and can be processed into films using solution casting. After solvent evaporation, post-heat treatment further promotes cross-linking and imidization. This process route addresses both the needs of cross-linked network construction and processing, solving the technical challenge of processing highly cross-linked materials. The raw materials used in the preparation method of this invention are all industrially available chemicals, the synthesis process is mature, and the reaction conditions are mild, making it suitable for large-scale production. The resulting thin film material can be widely used in flexible OLED display substrates, aerospace high-temperature sealing materials, flexible copper-clad laminates, high-temperature insulating tapes, flexible solar cell substrates, and other fields, possessing significant industrial value and broad market prospects. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the synthesis of the bisimidazole polyimide membrane of Example 1 of the present invention. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0021] Example 1 A method for preparing a tear-resistant and high-temperature resistant thin film material includes the following steps: (1) Preparation of a diamine monomer containing a diimidazole structure (BID-1): Under nitrogen protection, 350 g of polyphosphoric acid and 45 g of phosphorus pentoxide were added to a 1000 mL four-necked flask. Mechanical stirring was started, and the mixture was heated to 120 °C and held at this temperature for 1 hour to allow the solid to completely dissolve, resulting in a clear, viscous liquid. 18.5 g (0.10 mol) of 3,3'-diaminobiphenyl was weighed and slowly added to the above solution, and the mixture was stirred at 140 °C for 1.5 hours. 27.8 g (0.20 mol) of p-aminobenzoic acid was weighed and added to the reaction system in batches. After the addition was complete, the temperature was gradually increased to 190 °C, and the reaction was maintained at this temperature for 22 hours.

[0022] After the reaction was complete, the hot reaction solution was slowly poured into a stainless steel container containing 3000 mL of deionized water while stirring. A large amount of brown flocculent precipitate formed. After settling, the supernatant was discarded, and the precipitate was transferred to a Buchner funnel for filtration, collecting the filter cake. The filter cake was redispersed in 2000 mL of a 5 wt% sodium bicarbonate aqueous solution and stirred at room temperature for 2 hours, continuously adding sodium bicarbonate to maintain the pH at 8–9. The mixture was then filtered, and the filter cake was washed three times with 500 mL of deionized water each time. The washed filter cake was then placed in a vacuum drying oven and dried at 60°C for 24 hours to obtain the crude product.

[0023] The crude product was added to 500 mL of anhydrous ethanol and heated to 65 °C under reflux with stirring for 3 h for hot extraction purification. The mixture was hot-filtered, and the filtrate was collected. After cooling naturally to room temperature, the filtrate was placed in a 4 °C refrigerator and allowed to stand overnight, resulting in the precipitation of yellow crystals. The crystals were filtered under vacuum, washed with a small amount of cold ethanol, and dried in a vacuum drying oven at 50 °C for 24 h to obtain the purified diamine monomer containing a diimidazole structure (BID-1) in 58% yield.

[0024] (2) Preparation of polyamic acid prepolymer solution: Under nitrogen protection, 2.0028 g (10.0 mmol) of 4,4'-diaminodiphenyl ether (ODA) and 35.0 mL of N,N-dimethylacetamide (DMAc) dried with molecular sieves were added to a 250 mL dry three-necked flask and stirred at room temperature until completely dissolved. The flask was then cooled to -5 to 0 °C in an ice-salt bath, and 2.2248 g (10.2 mmol) of pyromellitic dianhydride (PMDA) was added in portions with vigorous stirring, controlling the addition rate to keep the reaction system temperature below 5 °C. After the addition was complete, the reaction was continued to be stirred in an ice bath for 6 h to obtain a viscous and transparent polyamic acid prepolymer solution with a solid content of approximately 12 wt%.

[0025] (3) Chain extension and crosslinking reaction: 0.198 g of BID-1 monomer prepared in step (1) (based on 5% of the molar amount of ODA) was dissolved in 8 mL of DMAc and slowly added dropwise to the polyamic acid prepolymer solution prepared in step (2). The dropwise addition process was completed within 30 min. After the addition was completed, the ice bath was removed, and the temperature was naturally raised to 35 °C. The reaction was continued for 30 h under nitrogen protection with stirring to obtain the modified polyamic acid prepolymer solution.

[0026] (4) Imidization reaction and film formation: The modified polyamic acid prepolymer solution obtained in step (3) was cooled to room temperature. A pre-mixed dehydrating agent (5.1 g acetic anhydride and 5.05 g triethylamine, prepared at a molar ratio of PMDA:dehydrating agent = 1:5) was slowly added while stirring. After addition, the mixture was stirred at room temperature for 24 h to carry out chemical imidization. After the reaction was complete, the reaction solution was slowly poured into a beaker containing 1000 mL of anhydrous ethanol while stirring rapidly, precipitating fibrous solids. After settling, the supernatant was discarded, and the solid was collected by filtration. The solid was washed three times with 100 mL of anhydrous ethanol each time. The washed solid was then dried in a vacuum drying oven at 60 °C for 12 h to obtain cross-linked polyimide resin.

[0027] The obtained cross-linked polyimide resin was redissolved in DMAc at a concentration of 15 wt%. After degassing by pressure filtration through a 0.45 μm polytetrafluoroethylene microporous membrane, the solution was allowed to stand for 2 hours to obtain a casting solution. The casting solution was uniformly cast onto a clean glass plate, placed on a horizontal platform, and dried in an 80℃ forced-air drying oven for 12 hours to allow the solvent to evaporate slowly. The glass plate was transferred to a programmable temperature controlled muffle furnace and treated sequentially at 120℃, 200℃, and 280℃ for 1 hour each at a heating rate of 3℃ / min, and finally treated at 350℃ for 2 hours for heat post-treatment. After naturally cooling to room temperature, the glass plate was immersed in 60℃ deionized water to allow the film to peel off automatically, obtaining a tear-resistant and high-temperature resistant film material. The thickness was measured by a thickness gauge and found to be uniform, with an average thickness of approximately 25 μm. Figure 1 This is a flowchart illustrating the synthesis process of the bisimidazole polyimide membrane in Example 1 of the present invention.

[0028] Example 2 The preparation method of this embodiment is basically the same as that of Example 1. The difference is that the amount of BID-1 monomer added in step (3) is adjusted to 12% (0.475g) of the molar amount of ODA, and the thickness of the resulting film is about 26μm.

[0029] Example 3 The preparation method of this embodiment is basically the same as that of Example 1. The difference is that the amount of BID-1 monomer added in step (3) is adjusted to 20% of the molar amount of ODA (0.792g), and the thickness of the resulting film is about 26μm.

[0030] Example 4 The preparation method of this embodiment is basically the same as that of Example 2, except that the polar aprotic solvent used in step (2) is a mixture of equal volumes of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0031] Comparative Example 1 The preparation method of this comparative example is basically the same as that of Example 1, except that BID-1 monomer is not added in step (3), that is, no chain extension and crosslinking reaction is performed. The resulting film is a linear polyimide film with a thickness of about 25 μm.

[0032] Comparative Example 2 This comparative example uses a traditional inorganic filler reinforcement method to prepare a polyimide composite film: 0.6 wt% of nano-silica was added to the polyamic acid prepolymer solution in step (2) of Example 1 to replace the BID-1 monomer. After ultrasonic dispersion for 2 hours, imidization and film formation were carried out in the same manner, and the resulting film thickness was about 26 μm.

[0033] The thin film materials prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests, and the test methods are as follows: (1) Glass transition temperature (Tg): Measured using a TA Q800 dynamic thermomechanical analyzer in tensile mode, at a frequency of 1 Hz, a heating rate of 5 °C / min, and a nitrogen atmosphere, in accordance with GB / T 40396-2021.

[0034] (2) Coefficient of thermal expansion (CTE): The average CTE was calculated using a TA Q400 thermomechanical analyzer with a heating rate of 5℃ / min and a nitrogen atmosphere. The test range was 50~350℃. The average CTE was calculated using the two heating curves.

[0035] (3) Thermal stability (Td5%): The 5% weight loss temperature was recorded using a TA Q50 thermogravimetric analyzer with a heating rate of 10℃ / min and a nitrogen atmosphere.

[0036] (4) Tensile properties: An Instron 5943 universal testing machine was used. The samples were cut into dumbbell shapes with a gauge length of 20 mm and a width of 4 mm. The tensile rate was 10 mm / min. Five samples were tested in each group and the average value was taken. The test was conducted in accordance with GB / T 1040.3-2006.

[0037] (5) Fracture energy (tear resistance): The single-sided notch tensile test method was adopted. The sample size was 30mm×5mm, the pre-made notch was 1.0mm, the tensile rate was 10mm / min, and the fracture energy Gc was calculated according to the Greensmith method.

[0038] The test results are shown in Table 1.

[0039] Table 1. Comparison of film performance between each embodiment and the comparative example. The test results in Table 1 show that: The tear-resistant and high-temperature resistant thin film materials prepared in Examples 1-4 of this invention all have glass transition temperatures above 410℃, with a maximum of 446℃; 5% thermal decomposition temperatures exceeding 550℃, with a maximum of 575℃; thermal expansion coefficients reduced to below 9ppm / K, with a minimum of 4.2ppm / K; tensile strengths exceeding 180MPa, with a maximum exceeding 230MPa; and fracture energies all exceeding 160kJ / m. 2 The highest value reached 211.3 kJ / m 2 It has excellent overall performance, combining high heat resistance, high strength, and excellent tear resistance.

[0040] Compared with Comparative Example 1 (linear pure PI), the crosslinked polyimide films prepared in Examples 1-3 of this invention show significant improvements in all thermal and mechanical properties, indicating that the introduction of a rigid bisimidazole structure and chain extension crosslinking effectively enhances the rigidity of the molecular chain and the network structure.

[0041] Compared with Comparative Example 2 (nano SiO2 / PI composite film), the embodiments of the present invention maintain a high elongation at break (>7.5%) while improving strength, and the fracture energy is significantly improved, indicating that the hydrogen bond cross-linking network constructed by molecular structure design has better toughening and tear resistance than inorganic filler dispersion.

[0042] Application Example 1 The tear-resistant and high-temperature resistant thin film material prepared in Example 2 was cut into 50mm × 10mm strips and used as flexible OLED display substrates for folding resistance testing. The strips were fixed on a self-made folding tester with a folding radius of 3mm, a folding angle of 180°, and a folding frequency of 30 times / minute. After 100,000 tests, no visible cracks were found on the film surface, and no microcracks were observed under an optical microscope (100x magnification), indicating that the thin film material of the present invention has excellent folding resistance and reliability.

[0043] Application Example 2 The tear-resistant and high-temperature resistant thin film material prepared in Example 2 was precisely cut and laminated using hot pressing to form a 2mm thick sealing gasket, which was then assembled on a high-temperature friction and wear testing machine for simulated testing. Test conditions: 40CrNiMoA steel ring as the mating part, temperature 350℃, load 150N, linear velocity 0.5m / s, test time 50h. After the test, the sealing gasket surface remained intact, without cracking or softening, with an average friction coefficient of 0.23 and low wear. The results show that the tear-resistant and high-temperature resistant thin film material provided by this invention meets the requirements for temperature resistance, mechanical strength, and friction performance under high-temperature dynamic sealing conditions.

[0044] As can be seen from the above embodiments and application examples, the tear-resistant and high-temperature resistant thin film material provided by the present invention has high temperature resistance, high strength, high toughness and excellent tear resistance, which can meet the stringent requirements of flexible display, aerospace and other fields, and has important application value and industrialization prospects.

[0045] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a tear-resistant and high-temperature resistant thin film material, characterized in that, Includes the following steps: (1) Preparation of diamine monomers containing a diimidazole structure: Aromatic aminobenzoic acid derivatives and aromatic diamine compounds are used as raw materials to carry out cyclization reaction in an acidic dehydration medium to obtain diamine monomers containing a diimidazole structure; (2) Preparation of polyamic acid prepolymer solution: Dissolve aromatic diamine monomer in a polar aprotic solvent, stir to dissolve, add aromatic dianhydride monomer, and carry out polymerization reaction under low temperature conditions to obtain polyamic acid prepolymer solution; (3) Crosslinking modification reaction: The diamine monomer containing the bisimidazole structure obtained in step (1) is mixed with the polyamic acid prepolymer solution obtained in step (2) and a chain extension crosslinking reaction is carried out to obtain the modified polyamic acid prepolymer. (4) Imidification reaction: The modified polyamic acid prepolymer obtained in step (3) is mixed with a dehydrating agent and subjected to an imidization reaction. After post-treatment, a tear-resistant and high-temperature resistant polyimide film material is obtained.

2. The method for preparing a tear-resistant and high-temperature resistant thin film material according to claim 1, characterized in that, In step (1), the aromatic diamine compound is one or more of 3,3'-diaminobiphenyl, 4,4'-diaminobiphenyl, and 3,4'-diaminobiphenyl; the aromatic aminobenzoic acid derivative is one or more of p-aminobenzoic acid, m-aminobenzoic acid, and o-aminobenzoic acid.

3. The method for preparing a tear-resistant and high-temperature resistant thin film material according to claim 1, characterized in that, In step (2), the aromatic diamine monomer is one or more of 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 3,3'-diaminodiphenyl ether; the aromatic dianhydride monomer is one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride.

4. The method for preparing a tear-resistant and high-temperature resistant thin film material according to claim 1, characterized in that, In step (3), the amount of diamine monomer containing the diimidazole structure added is 2-25 mol of the aromatic diamine monomer.

5. The method for preparing a tear-resistant and high-temperature resistant thin film material according to claim 1, characterized in that, In step (4), the dehydrating agent is a mixture of acetic anhydride and tertiary amine compounds, and the molar ratio of acetic anhydride to tertiary amine compounds is 1:0.8 to 1.2; the tertiary amine compounds are one or more of triethylamine, pyridine, and N,N-dimethylaniline.

6. A tear-resistant and high-temperature resistant thin film material, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

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