Repairable polyimide film based on cooperation of multiple dynamic bonds and preparation method of repairable polyimide film

Abstract

The invention discloses a repairable polyimide film based on multiple dynamic bond synergy and a preparation method of the repairable polyimide film, and belongs to the field of polyimide film production. Comprising the following steps: stirring and mixing diamine and a solvent, adding dianhydride step by step, and reacting to obtain polyamide acid resin; dispersing a chain extender in a solvent to obtain a dispersion liquid A; dispersing coordination ion liquid in a solvent to obtain dispersion liquid B; sequentially adding the dispersion liquid A and the dispersion liquid B into polyamide acid resin, stirring for polymerization reaction to obtain composite polyamide acid resin, and performing vacuum defoaming; casting the composite polyamide acid resin subjected to vacuum defoaming to remove a solvent, so as to obtain a self-supporting membrane; and carrying out thermal imidization, removing the solvent, and carrying out longitudinal and transverse stretching to obtain the product. The polyimide film has the characteristics of high mechanical property, good dimensional stability, self-repairing and the like, and can be applied to the fields with high-performance requirements, such as 5G communication, AI models, flexible display, new energy automobiles, medical health and the like.

Description

Technical Field

[0001] This invention belongs to the field of polyimide film production, specifically relating to a repairable polyimide film based on multiple dynamic bond synergy and its preparation method. Background Technology

[0002] With the advent of the AI ​​era and the development of electronic packaging technology, electronic components and devices are becoming increasingly high-performance, miniaturized, and highly integrated. Their operating environments are also becoming more complex and variable, placing increasingly higher demands on materials. Under harsh operating conditions, materials are affected by stress concentration and uneven temperature distribution during service, leading to various cracks and damage both internally and externally, significantly reducing their performance and lifespan. Therefore, scientists have been dedicated to the research of smart materials, aiming to endow materials with self-healing capabilities, thereby improving their overall performance and extending their service life.

[0003] Self-healing materials can be broadly classified into two categories based on their mechanism: exogenous self-healing and intrinsic self-healing. Exogenous self-healing materials primarily achieve self-repair by encapsulating microcapsules, hollow fibers, or microvascular networks, releasing polymerizable or cross-linked components. Their repair capacity depends on the remaining amount of repair agent; once the repair agent is depleted, the ability to self-repair at the same location is permanently lost. Intrinsic self-healing materials, on the other hand, do not require external addition. They utilize dynamic and reversible chemical bonds within the material's molecular structure to complete reversible bonding reactions at the fracture site, thereby achieving repair and restoring the material's original properties and characteristics. Common dynamic and reversible chemical bonds include hydrogen bonds, coordination bonds, ionic bonds, and π-π stacking. In contrast, intrinsic self-healing materials are unaffected by the content and distribution of external repair agents. Instead, they utilize specific and reversible interactions within the matrix, enabling them to repeatedly repair the same damaged area, making them faster and more effective—one of the more efficient methods for developing self-healing materials.

[0004] Polyimide (PI) is a class of polymers containing an imide ring (-CO-N-CO-) in its main chain. It has excellent heat resistance, mechanical properties, electrical properties and chemical stability, and has been widely used in aerospace, rail transportation, new energy vehicles, medical devices, low-altitude flight, bionic robots and other technical fields.

[0005] Although polyimides possess excellent mechanical, electrical, and chemical resistance properties, traditional polyimides are mostly disposable materials lacking self-healing capabilities. Especially in thin-film products, their surfaces are highly susceptible to scratches and mechanical damage under complex stress and extreme environments, leading to irreversible damage, performance degradation, and even failure. This, in turn, affects the stability of their use in FCCLs and flexible displays, resulting in device scrapping. Therefore, providing a polyimide material with superior self-healing capabilities and good thermodynamic properties has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a repairable polyimide film based on multiple dynamic bond synergy and its preparation method, thereby solving the problems in the prior art.

[0007] The objective of this invention can be achieved through the following technical solutions: The method for preparing a repairable polyimide film based on multiple dynamic bond synergy includes the following steps: After mixing the diamine with the solvent, dianhydride was added in steps to react and obtain polyamic acid resin. The chain extender is dispersed in a solvent to obtain dispersion A; Dispersion B is obtained by dispersing the complexed ionic liquid in a solvent; Dispersion A and dispersion B were added to polyamic acid resin in sequence, and the mixture was stirred to carry out a polymerization reaction to obtain composite polyamic acid resin, which was then subjected to vacuum degassing. The composite polyamic acid resin after vacuum degassing is cast and desolventized to obtain a self-supporting film; then it is subjected to thermal imidization to remove the solvent, and then stretched longitudinally and laterally to obtain the final product.

[0008] Furthermore, the molar ratio of the diamine to the dianhydride is 1:0.95 to 1.015.

[0009] Furthermore, the viscosity of the polyamic acid resin is 80-200 Pa·s.

[0010] Further, the diamine is one or more selected from 6,6'-diamino-3,3'-methylenedibenzoic acid (MBAA), 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzoylaniline (DABA), 2,2-bis[(4-aminophenoxy)phenyl]propane, 1,3-bis(3-aminophenoxy)benzene, 1,2-bis(4-aminophenoxy)ethane, and 1,4-bis(4-aminophenoxy)benzene; The dianhydride is one or more of the following: pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic anhydride, 4,4'-diphenyl ethertetracarboxylic anhydride, bisphenol A type diether dianhydride, p-biphenylene-bisphenyltriester dianhydride, and 4,4'-terephthalodioxydiphthalic anhydride.

[0011] Furthermore, the chain extender is one or more of bio-based small molecule acids, diethylenetriamine, and diacetylatediamine; the bio-based small molecule acid is one or two of citric acid and sebacic acid.

[0012] Furthermore, the coordination ionic liquid is Zn. 2+ Fe 3+ Al 3+ Sn 4+ One or two of the acetate complex solutions.

[0013] Furthermore, the amount of chain extender added is 5-30% of the molar amount of polyamic acid resin; the amount of coordination ionic liquid added is 1-10% of the solid content of polyamic acid resin.

[0014] Furthermore, the conditions for thermal imidization are: a 50°C gradient temperature increase treatment within the range of 100-450°C.

[0015] A repairable polyimide film is prepared using the above-described preparation method.

[0016] The above-mentioned application of repairable polyimide films in the fabrication of flexible display devices.

[0017] The beneficial effects of this invention are: 1. This invention firstly employs diamine and dianhydride monomers containing flexible groups, which can improve the fluidity of the polyimide molecular chain, effectively reduce the material's Tg, and lower the energy barrier for the self-healing process; it selects diamine and dianhydride monomers containing carboxyl groups, which can complex and coordinate with metal ion liquids to form dynamic ion clusters, serving as energy dissipation centers to enhance toughness and realize the material's self-healing function; at the same time, it selects diamine and dianhydride monomers containing polybenzene ring structures, such as naphthalene dianhydride, which, in addition to providing the material's rigid domain and mechanical support, can provide π-π stacking sites, whose π-π stacking effect can activate and repair deep damage to the material at high temperatures (≥130℃).

[0018] 2. By introducing a chain extender, the reaction of small molecule acids with amines can form more amide bonds, thereby forming hydrogen bond physical crosslinking points between polyimide molecules and between molecular chains, which greatly reduces the material's self-healing activation energy.

[0019] 3. This invention further enhances the self-healing ability of materials by adding metal coordination ionic liquid to form coordination ionic bonds with carboxyl groups on the molecular chain.

[0020] 4. In terms of the preparation process control of the seeding mill, the present invention guides the microphase separation of soft segments (dynamic bond enrichment area) and hard segments (imide crystal area) through two-step temperature-progressive imidization (180℃ pre-curing → 450℃ final curing), thereby realizing the functional separation of "repair channel" and "support skeleton". Through the synergistic repair of multiple dynamic bonds and the microphase separation structure, the invention can obtain polyimide films with good mechanical properties, excellent processing performance and self-healing properties. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] A repairable polyimide film based on multiple dynamic bond synergy and its preparation method include the following steps: S1, add diamine to the reaction vessel, then add solvent and stir to dissolve, then add dianhydride step by step to react and obtain polyamic acid resin; S2, add the chain extender to the dispersion vessel, add solvent and stir to disperse, to obtain dispersion A; S3, the coordinated ionic liquid is added to the dispersion vessel, and solvent is added and stirred to disperse, thus obtaining dispersion B; S4, Dispersion A and dispersion B are added to polyamic acid resin in sequence, stirred to carry out in-situ polymerization reaction, and composite polyamic acid resin is obtained, and vacuum degassing is performed. S5, the composite polyamic acid resin after vacuum degassing is cast and desolventized to obtain a self-supporting film; S6, the self-supporting film is thermally imidized, the solvent is further removed, and then longitudinally and laterally stretched to obtain the final product.

[0023] In S1, the molar ratio of diamine to dianhydride is 1:0.95 to 1.015; the viscosity of the polyamic acid resin is 80-200 Pa·s.

[0024] In S1, the diamine is one or more of 6,6'-diamino-3,3'-methylenedibenzoic acid (MBAA), 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminobenzoylaniline (DABA), 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP), 1,3-bis(3-aminophenoxy)benzene (APB), 1,2-bis(4-aminophenoxy)ethane (APE), and 1,4-bis(4-aminophenoxy)benzene (TPE-Q).

[0025] In S1, the dianhydride is one or more of the following: pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid (DCB), 1,4,5,8-naphthalenetetracarboxylic anhydride (NTDA), 4,4'-diphenyl ether tetracarboxylic anhydride (ODPA), bisphenol A type diether dianhydride (BPADA), p-biphenyl-bisphenyltriester dianhydride (BP-TME), and 4,4'-terephthalodioxydiphthalic anhydride (HQDPA).

[0026] In S2, the chain extender is one or more of bio-based small molecule acids, diethylenetriamine, and diacetylatediamine; the bio-based small molecule acid is one or two of citric acid and sebacic acid.

[0027] In S2, the stirring and dispersion is a shear dispersion, with a rotation speed of 500-1500 r / min, a dispersion time of 2-3 h, and a temperature of 50-80℃.

[0028] In S3, the coordination ionic liquid is Zn 2+ Fe 3+ Al 3+ Sn 4+ One or two of the acetate complex solutions.

[0029] In S1-S3, the solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0030] In S4, the amount of chain extender added is 5-30% of the molar amount of polyamic acid resin; the amount of coordination ionic liquid added is 1-10% of the solid content of polyamic acid resin.

[0031] In S4, the reaction temperature is 30-60℃, and the stirring reaction time is 4-8h; preferably, the viscosity of the composite polyamic acid resin is 50-150 Pa·s.

[0032] In S5, the casting temperature is 160-220℃ and the casting speed is 3-6m / min.

[0033] In S6, the conditions for thermal imidization are: a 50°C gradient temperature increase from 100 to 450°C; the ratio of longitudinal stretching is 1:(1-1.1), and the ratio of transverse stretching is 1:(1-1.2).

[0034] The technical solution of the present invention will be described below through the following embodiments; the sources of some of the raw materials are as follows: Zn 2+ Coordination ionic liquid: Manufacturer: Aladdin, Brand: Z119378.

[0035] Example 1 A repairable polyimide film, prepared by the following method: S1. First, 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP) and 6,6'-bisamino-3,3'-methylenedibenzoic acid ((MBAA)) are dissolved in N,N-dimethylacetamide. After complete dissolution, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid (DCB) is added in batches for reaction. The molar ratio of BAPP, MBAA and DCB is 3:7:9.8-10.15 to obtain polyamic acid (PAA) resin. The viscosity of PAA resin is controlled at 120 Pa·s. S2. Citric acid and diethylenetriamine are added to a dispersion vessel, and N,N-dimethylacetamide is added for stirring and dispersion. The stirring speed is 1000 r / min, the temperature is controlled at 60℃, and the stirring time is 3 h to obtain dispersion A. The molar ratio of citric acid to diethylenetriamine is 1:2, and the amount of citric acid used is 5% of the molar weight of PAA resin. S3. Add the Zn²⁺ complexing ionic liquid to the dispersion vessel, and add N,N-dimethylacetamide for stirring and dispersion. The stirring speed is 800 r / min, and the stirring time is 1 h to obtain dispersion B. The amount of complexing ionic liquid added is 5% of the solid content of PAA resin.

[0036] S4. Add the above dispersion A and dispersion B to the PAA resin and stir to allow the chain extender, ionic complex liquid and PAA matrix to undergo in-situ polymerization reaction to form a copolymer. Stir the reaction for 4 hours to obtain PAA resin with complete polymerization reaction and control the resin viscosity to 110 Pa·s. S5. The PAA resin is cast and desolventized on a mirror steel strip at a casting temperature of 175°C and a casting speed of 3.2 m / min to obtain a self-supporting film. S6. The self-supporting film is thermally imidized under a gradient temperature increase of 100-450℃ (starting from the first oven at 100℃, each imidization oven increases by 50℃, 100℃, 150℃, 200℃, 250℃... until it reaches 450℃), and then subjected to longitudinal stretching and transverse stretching. The longitudinal stretching ratio is 1.0, and the transverse stretching ratio is 1.02, thus obtaining a polyimide film.

[0037] Example 2 A repairable polyimide film is prepared using a method different from that in Example 1, except for step S2. Specifically, step S2 is as follows: citric acid and diethylenetriamine are added to a dispersion vessel, and N,N-dimethylacetamide is added for stirring and dispersion. The stirring speed is 1000 r / min, the temperature is controlled at 60℃, and the stirring time is 3 h to obtain dispersion A. The molar ratio of citric acid to diethylenetriamine is 1:2, and the amount of citric acid used is 10% of the molar amount of PAA resin. All other steps and conditions are the same as in Example 1.

[0038] Example 3 A repairable polyimide film is prepared in a method that differs from that in Example 1 only in step S1. Specifically, step S1 is as follows: 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP) and 6,6'-bisamino-3,3'-methylenedibenzoic acid ((MBAA)) are first dissolved in N,N-dimethylacetamide. After complete dissolution, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid (DCB) and 1,4,5,8-naphthalenetetracarboxylic anhydride ((NTDA)) are added in batches for reaction. The molar ratio of BAPP, MBAA, DCB, and NTDA is 3:7:3:6.8-7.15 to obtain PAA resin. The viscosity of PAA resin is controlled to be 120 Pa·s. All other steps and conditions are the same as in Example 1.

[0039] Example 4 A repairable polyimide film, the preparation method of which differs from that of Example 1 only in steps S1 and S2, specifically: S1. First, 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP) and 6,6'-bisamino-3,3'-methylenedibenzoic acid ((MBAA)) are dissolved in N,N-dimethylacetamide. After complete dissolution, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid (DCB) and 1,4,5,8-naphthalenetetracarboxylic anhydride ((NTDA)) are added in batches for reaction. The molar ratio of BAPP, MBAA, DCB and NTDA is 3:7:3:6.8-7.15 to obtain PAA resin. The viscosity of PAA resin is controlled at 120 Pa·s. S2. Add sebacic acid and diethylenetriamine to a dispersion vessel, and add N,N-dimethylacetamide for stirring and dispersion. The stirring speed is 1000 r / min, the temperature is controlled at 60℃, and the stirring time is 3 h to obtain dispersion A. The molar ratio of sebacic acid to diethylenetriamine is 1:2, and the amount of sebacic acid used is 10% of the molar amount of PAA resin. All other steps and conditions are the same as in Example 1.

[0040] Example 5 A repairable polyimide film, the preparation method of which differs from that of Example 1 only in steps S1 and S2, specifically: S1. First, 2,2-bis[(4-aminophenoxy)phenyl]propane (BAPP) and 6,6'-bisamino-3,3'-methylenedibenzoic acid ((MBAA)) are dissolved in N,N-dimethylacetamide. After complete dissolution, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid (DCB) and 1,4,5,8-naphthalenetetracarboxylic anhydride ((NTDA)) are added in batches for reaction. The molar ratio of BAPP, MBAA, DCB and NTDA is 3:7:3:6.8-7.15 to obtain PAA resin. The viscosity of PAA resin is controlled at 120 Pa·s. S2. Citric acid, sebacic acid, and diethylenetriamine are added to a dispersion vessel, and N,N-dimethylacetamide is added for stirring and dispersion. The stirring speed is 1000 r / min, the temperature is controlled at 60℃, and the stirring time is 3 h to obtain dispersion A. The molar ratio of citric acid, sebacic acid, and diethylenetriamine is 0.5:0.5:2, and the sum of the amounts of citric acid and sebacic acid is 10% of the molar amount of PAA resin. All other steps and conditions are the same as in Example 1.

[0041] Comparative Example 1 The preparation method for conventional polyimide films is as follows: S1. First, 4,4-diaminodiphenyl ether (ODA) is dissolved in N,N-dimethylacetamide, and then pyromellitic dianhydride (PMDA) is added to react. The molar ratio of ODA to PMDA is 1:0.98-1.015 to obtain PAA resin. The viscosity of PAA resin is controlled to be 120 Pa·s. S2. The PAA resin is cast onto a mirror steel strip at a casting temperature of 175°C and a casting speed of 5 m / min to form a self-supporting film. S3. The self-supporting film is thermally imidized under a gradient temperature increase of 100-450℃ (starting from the first oven at 100℃, each imidization oven increases by 50℃, 100℃, 150℃, 200℃, 250℃... until it reaches 450℃), and then longitudinally stretched and transversely stretched. The longitudinal stretching ratio is 1.0 and the transverse stretching ratio is 1.15, thus obtaining a conventional polyimide film.

[0042] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that no chain extender is used, i.e., there is no step S2, and no dispersion A is used in step S4. All other aspects are the same as in Example 1.

[0043] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the coordination ionic liquid is not used, i.e., step S3 is not used, and step S4 does not have dispersion B. All other aspects are the same as Example 1.

[0044] Performance testing The polyimide films prepared in Examples 1-5 and Comparative Example 1 were subjected to performance tests; the test items and procedures included: 1) Glass transition temperature (Tg): GB / T36800.2, cut the thin film sample into strips of 5mm×1cm, and then heat it from 25℃ to 500℃ at a heating rate of 5℃ / min on a TMA tester, and read the Tg data. 2) Original tensile strength: GB / T1040.1, cut the film into 15cm pieces. A 1.5cm specimen is stretched on a tensile testing machine at a speed of 5m / min until it breaks, and the breaking strength is then checked. 3) Original elongation at break: GB / T1040.1, cut the film into 15cm pieces. Take a 1.5cm specimen and stretch it on a tensile testing machine at a speed of 5m / min until the specimen breaks. Then check the elongation at break. 4) Tensile strength at 130℃ for 4 hours (self-healing): GB / T1040.1. Cut the self-healed film into 15cm pieces. A 1.5cm specimen is stretched on a tensile testing machine at a speed of 5m / min until it breaks, and the breaking strength is then checked. 5) Elongation at break after self-healing at 130℃ for 4 hours: GB / T1040.1. Cut the self-healed film into 15cm pieces. Take a 1.5cm specimen and stretch it on a tensile testing machine at a speed of 5m / min until the specimen breaks. Then check the elongation at break. 6) Self-healing efficiency: Enterprise standard, compare the tensile strength of the specimen before fracture with the tensile strength of the specimen after fracture and self-healing at 130℃ for 4 hours.

[0045] The test results are shown in Table 1 below: Table 1. Performance test results of polyimide films The method for testing the 130℃ self-healing tensile strength after 4 hours involves allowing the sample to self-heal at 130℃ for 4 hours after breakage, followed by testing the tensile strength using the same method. The self-healing efficiency is calculated based on the recovery effect of the sample's tensile strength.

[0046] Based on the results in Table 1, the following analysis is performed: 1. By comparing Example 1 and Comparative Example 1, it can be found that: Conventional polyimide films do not have self-healing capabilities. By using flexible monomers and adding chain extenders and ionic coordination solutions, the film can acquire self-healing capabilities through hydrogen bonding and coordination bond interactions. After self-healing at 130℃ for 4 hours, the tensile strength of the film can be restored to 88.89%.

[0047] 2. By comparing Example 1 and Comparative Example 2, it can be found that: Adding only ionic coordination solution results in a weak self-healing ability of the film. After 4 hours of self-healing at 130℃, the tensile strength of the film only recovered to 50.86%. This is because the film's molecular chains have a weak ability to pair with each other due to the coordination interaction of ionic bonds alone, resulting in a low-efficiency recovery effect.

[0048] 3. By comparing Example 1 and Comparative Example 3, it can be found that: Adding only chain extender can restore 71.60% of the tensile strength of the film after self-healing at 130℃ for 4 hours. This is not as good as the combined effect of chain extender and ion coordination liquid. This is because the ability of film molecular chains to re-pair is limited by hydrogen bond interaction alone, and the self-healing ability cannot reach the best effect.

[0049] 4. By comparing Examples 1-5, it can be found that: By using naphthalene monomer, along with various chain extenders and ionic coordination solutions, the film exhibits superior self-healing ability. This is because naphthalene monomer can form a π-π stacking effect, and the combination of multiple chain extenders and their increased amounts can form stronger hydrogen bond interactions. Combined with ionic coordination interactions, these factors result in a more efficient self-healing ability for the film. After self-healing at 130℃ for 4 hours, the tensile strength can recover to 95.76%.

[0050] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a repairable polyimide film based on multiple dynamic bond synergy, characterized in that, Includes the following steps: After mixing the diamine with the solvent, dianhydride was added in steps to react and obtain polyamic acid resin. The chain extender is dispersed in a solvent to obtain dispersion A; Dispersion B is obtained by dispersing the complexed ionic liquid in a solvent; Dispersion A and dispersion B were added to polyamic acid resin in sequence, and the mixture was stirred to carry out a polymerization reaction to obtain composite polyamic acid resin, which was then subjected to vacuum degassing. The composite polyamic acid resin after vacuum degassing is cast and desolventized to obtain a self-supporting film; then it is subjected to thermal imidization to remove the solvent, and then stretched longitudinally and laterally to obtain the final product.

2. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The molar ratio of the diamine to the dianhydride is 1:0.95 to 1.

015.

3. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The viscosity of the polyamic acid resin is 80-200 Pa·s.

4. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The diamine is one or more selected from 6,6'-diamino-3,3'-methylenedibenzoic acid (MBAA), 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzoyl aniline (DABA), 2,2-bis[(4-aminophenoxy)phenyl]propane, 1,3-bis(3-aminophenoxy)benzene, 1,2-bis(4-aminophenoxy)ethane, and 1,4-bis(4-aminophenoxy)benzene; The dianhydride is one or more of the following: pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic anhydride, 4,4'-diphenyl ethertetracarboxylic anhydride, bisphenol A type diether dianhydride, p-biphenylene-bisphenyltriester dianhydride, and 4,4'-terephthalodioxydiphthalic anhydride.

5. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The chain extender is one or more of bio-based small molecule acids, diethylenetriamine, and diacetylatediamine; the bio-based small molecule acid is one or two of citric acid and sebacic acid.

6. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The coordination ionic liquid is Zn. 2+ Fe 3+ Al 3+ Sn 4+ One or two of the acetate complex solutions.

7. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The amount of chain extender added is 5-30% of the molar amount of polyamic acid resin; the amount of coordination ionic liquid added is 1-10% of the solid content of polyamic acid resin.

8. The method for preparing a repairable polyimide film based on multiple dynamic bond synergy according to claim 1, characterized in that, The conditions for thermal imidization are: a 50°C gradient temperature increase within the range of 100-450°C.

9. A repairable polyimide film, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the repairable polyimide film according to claim 9 in the preparation of flexible display devices.

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