A high heat-resistant thermosetting polyimide resin and its preparation method

Abstract

This invention relates to the field of polyimide resin technology, specifically to a high-heat-resistant thermosetting polyimide resin and its preparation method. The method includes: mixing aromatic dianhydride, aromatic heterocyclic diamine, siloxane-containing diamine, and 4-phenylethynyl phthalic anhydride in an organic solvent, and performing a polycondensation reaction at room temperature to obtain a polyamic acid solution; preparing a polyimide oligomer solution from the polyamic acid solution using a chemical imidization method, followed by washing, filtration, and drying to obtain a thermosetting polyimide oligomer powder; cold-pressing the thermosetting polyimide oligomer powder into a mold, and then heat-sintering and curing to obtain a cured resin. This invention simultaneously introduces a high-heat-resistant heterocyclic diamine and a siloxane-containing diamine into the thermosetting polyimide resin system, synergistically improving the heat resistance of the material. Its comprehensive properties, including heat resistance, mechanical properties, and chemical stability, are excellent. Its close melting and crosslinking temperatures, i.e., a narrow processing window, allow for the development of new methods for PI resin powder molding.

Description

Technical Field

[0001] This invention relates to the field of polyimide resin technology, specifically to a high heat-resistant thermosetting polyimide resin and its preparation method. Background Technology

[0002] Polyimide (PI) is widely used in aerospace and other fields due to its excellent heat resistance, mechanical properties, and chemical stability. In recent years, the rapid development of the aerospace industry has forced PI and other specialty materials to withstand more extreme application environments, such as high and low temperatures, and to be lighter to meet the demands of long-distance, long-duration operation of aircraft. Therefore, developing high-performance PI that is more heat-resistant, lightweight, and high-strength has become a major challenge in the field. This presents not only the challenge of balancing various properties of polyimide (such as the difficulty in achieving a balance between lightweight and high strength), but also the fact that high-performance PI often has a narrow processing window and is difficult to mold due to increased molecular rigidity and enhanced intermolecular forces.

[0003] In the structural design and preparation of high-performance thermosetting resins, a common problem arises: the monomer / precursor structure is too rigid, resulting in a high melting point that is close to or higher than the resin's rapid reaction temperature, leading to a narrow processing window and making it impossible to process using traditional melt processing techniques. To date, researchers both domestically and internationally have developed thermosetting polyimide (PI) end-capped with norbornene, ethynyl, phenylethynyl, benzocyclobutene, and cyano groups. Among these, phenylethynyl-terminated PIs, which have been extensively studied, possess advantages such as high heat resistance, excellent chemical resistance, flame retardancy, and high mechanical strength. However, due to the rigid framework and strong π-π conjugated system, charge transfer complexation, and other intramolecular interactions, their high melting temperature, high melt viscosity, and low solubility limit their application range. Current research both domestically and internationally mainly addresses this issue by introducing flexible structures such as ether bonds, sacrificing some heat resistance to improve processing performance, or by using isomerically reactive monomers to increase intermolecular volume. However, the inherent contradiction between the processability and high performance of high-heat-resistant resins remains difficult to synergistically control. Summary of the Invention

[0004] Based on this, this invention utilizes the close melting and crosslinking temperatures of high-performance PI resins, i.e., a narrow processing window, to develop a new method for PI resin powder molding to prepare highly heat-resistant, lightweight porous polyimide materials. Furthermore, by studying structure-property relationships and optimizing structural design, the invention synergistically improves the heat resistance of the material by introducing highly heat-resistant heterocyclic diamines and siloxane-containing diamines. Simultaneously, it leverages the catalytic effect of aromatic heterocyclic structures to achieve dynamic exchange of organosilicon segments, thereby enhancing the crosslinking density and adhesion strength at the "fusion point" of the PI resin powder interface and promoting the release of local stress. Ultimately, this results in a new thermosetting PI resin system with high heat resistance, lightweight, and high strength, providing new ideas for the molding and processing of high-performance specialty resin materials.

[0005] To achieve the above objectives, on the one hand, the present invention provides a high heat-resistant thermosetting polyimide resin, wherein the general formula of the oligomer of the thermosetting polyimide resin is shown in formula (1):

[0006]

[0007] Where n = 1-20, and Ar is selected from any of the following structures:

[0008]

[0009] Rx represents an aromatic heterocyclic diamine fragment and a siloxane-containing diamine fragment, and the molar ratio of the aromatic heterocyclic diamine fragment and the siloxane-containing diamine fragment in formula (1) is (99-1):1;

[0010] The aromatic heterocyclic diamine fragment is selected from any of the following structures:

[0011]

[0012] The diamine fragment containing the siloxane structure is selected from any of the following structures:

[0013]

[0014] More preferably, in formula (1), n ​​= 2, and it has a symmetrical structure, wherein the diamine fragment containing the siloxane structure is located at the center, and the aromatic heterocyclic diamine fragments are located on both sides; even further, its preferred structure has the following:

[0015]

[0016]

[0017] According to another aspect of the present invention, the present invention also provides a method for preparing a high heat-resistant thermosetting polyimide resin, which specifically includes:

[0018] S1. Aromatic dianhydride, aromatic heterocyclic diamine, siloxane-containing diamine, and 4-phenylethynyl phthalic anhydride are mixed in an organic solvent and subjected to polycondensation reaction at 0-50°C to obtain a polyamic acid solution.

[0019] S2. Polyamic acid solution is prepared into polyimide oligomer solution by chemical imidization, and then washed, filtered and dried to obtain thermosetting polyimide oligomer powder.

[0020] S3. The thermosetting polyimide oligomer powder is cold-pressed into shape and then heat-sintered and cured to obtain a high heat-resistant thermosetting polyimide resin.

[0021] As a further preferred embodiment of the present invention, the aromatic dianhydride includes at least one of pyromellitic dianhydride (PMDA), 3,3,4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 4,4'-oxobisphthalic anhydride (ODPA), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), hexafluorodianhydride (6FDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), and 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA).

[0022] As a further preferred embodiment of the present invention, the aromatic heterocyclic diamine includes at least one of 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ), 2-(4-aminophenyl)-5-aminobenzoxazole (APBOA), 2-(4-amino,2-phenol)-5-aminobenzimidazole (HPABZ), 2-(4-amino,2-phenol)-5-aminopyridinium imidazole (HPYABZ), 2-(4-aminophenyl)-5-aminopyridinium imidazole (PYABZ), bis(2-hydroxy-4-aminophenyl)-1,4-phenylenepyridinium diimidazole (M5M), bis(2-hydroxy-4-aminophenyl)-1,4-phenylenebenzodioxazole (HDBOA), and 5-amino-2-(2-hydroxy-4-aminophenyl)-benzoxazole (HBOA).

[0023] As a further preferred embodiment of the present invention, the siloxane-containing diamine includes at least one of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (APTMDS), bis(4-aminophenyl)tetramethyldisiloxane, bis(3-aminophenyl)tetramethyldisiloxane, bis(4-aminophenyl)-1,3-dimethyl-1,3-diphenyldisiloxane, bis(4-aminophenoxy)dimethylsilane, and bis(4-aminophenoxy)methylphenylsilane.

[0024] As a further preferred embodiment of the present invention, the solid content of the polyamic acid solution is 10-50 wt%.

[0025] As a further preferred embodiment of the present invention, the molar ratio of acid anhydride to amino group is 1.01-3:1, based on the total amount of acid anhydride contained in aromatic dianhydride and 4-phenylethynylphthalic anhydride, and the total amount of amino group contained in aromatic heterocyclic diamine and siloxane-containing diamine.

[0026] As a further preferred technical solution of the present invention, the chemical imidization method includes: adding a dehydrating agent and a dehydrating catalyst to a polyamic acid solution, and stirring at room temperature to 150°C for 2-48 hours to obtain a polyimide oligomer solution; wherein the dehydrating agent is at least one of acetic anhydride, propionic anhydride, butyric anhydride, and sodium acetate, and the dehydrating catalyst is at least one of triethylamine, isoquinoline, pyridine, and N-methylpyridine.

[0027] As a further preferred embodiment of the present invention, the molar ratio of acid anhydride to amino group is 1.01-3:1, based on the total amount of acid anhydride contained in aromatic dianhydride and 4-phenylethynylphthalic anhydride, and the total amount of amino group contained in aromatic heterocyclic diamine and siloxane-containing diamine.

[0028] As a further preferred technical solution of the present invention, step S3 specifically includes: first, sieving the thermosetting polyimide oligomer powder with a sieve of 100 mesh or higher, then pressing it with a press at 0.1-100MPa for 1 min-3 h to form it, and finally heating it to 350-450℃ for heat sintering and curing for 0.5-10 h, and cooling it to room temperature to obtain a high heat-resistant thermosetting polyimide resin.

[0029] As a further preferred technical solution of the present invention, in step S1, the organic solvent is selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide.

[0030] As a further preferred technical solution of the present invention, in step S2, the detergent is at least one of deionized water, methanol, ethanol, propanol, and butanol.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] (1) The present invention introduces both high heat-resistant heterocyclic diamine and siloxane-containing diamine into the thermosetting polyimide resin system, which synergistically improves the heat resistance of the material and its comprehensive properties such as heat resistance, mechanical properties and chemical stability are excellent.

[0033] (2) This invention utilizes the dynamic exchange reaction of organosilicon segments to enhance the crosslinking density and bonding strength at the "fusion point" of PI resin powder interface. Moreover, the cured resin has a porous structure, which provides a new solution for developing thermosetting PI resin with high heat resistance and lightweight and high strength.

[0034] (3) The thermosetting polyimide resin prepared by the present invention exhibits good frictional characteristics after being impregnated with oil. Combined with its excellent thermal stability and mechanical properties, this provides the possibility for the development of high heat-resistant spacecraft long-life bearings and their components.

[0035] (4) This invention utilizes the close melting and crosslinking temperatures of thermosetting polyimide, i.e., the narrow processing window, to develop a new method for molding PI resin powder, and obtains high heat resistance and lightweight porous polyimide materials, providing a new approach for the molding and processing of special high-performance resin materials. Attached Figure Description

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] Figure 1 These are the infrared spectra of the thermosetting polyimide oligomer prepared in Example 1 of this invention before and after curing;

[0038] Figure 2 This is the 1H NMR spectrum of the thermosetting polyimide oligomer prepared in Example 1 of this invention;

[0039] Figure 3 This is the DSC curve of the thermosetting polyimide oligomer prepared in Example 1 of this invention;

[0040] Figure 4 These are the thermogravimetric curves of the thermosetting polyimide oligomer prepared in Example 1 of this invention before and after curing;

[0041] Figure 5 These are SEM images of the cross-section of the thermosetting polyimide resin strip prepared in Example 1 of this invention;

[0042] Figure 6 These are the DMA curves of the thermosetting polyimide resins prepared in Examples 1 and 2 of this invention;

[0043] Figure 7 This is a curve showing the change of the coefficient of friction of the thermosetting polyimide resin prepared in Example 1 of the present invention under different loads over time.

[0044] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0045] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0046] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0047] Example 1

[0048] 1) At room temperature, N-methylpyrrolidone (150 g) was added to a clean, dry three-necked flask of 250 mL. Under a nitrogen atmosphere, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (5.34 g) and 2-(4-aminophenyl)-5-aminobenzimidazole (9.64 g) were added separately. After they were completely dissolved, pyromellitic dianhydride (9.37 g) was added. The reaction was carried out at room temperature for 3 h. Then 4-phenylethynylphthalic anhydride (11.2 g) was added and the reaction was continued for 5 h for end-capping treatment.

[0049] 2) Add acetic anhydride (10.97 g) and isoquinoline (138.77 mg) to the above reaction flask and stir at room temperature for 12 h. Pour the mixture into 1000 mL of methanol to precipitate, wash repeatedly with methanol and filter, and finally dry the filter cake under vacuum at 190 °C for 4 h to obtain a yellow thermosetting polyimide oligomer (denoted as CP4).

[0050]

[0051] 3) The oligomer was pulverized and sieved through a 250-mesh sieve. The resulting powder was placed into a cold-pressing mold cavity and pressed for 30 minutes at a pressure of 50 MPa. The cold-pressed block was then cured in a vacuum oven using a curing process of 240℃-1h and 350℃-2h to finally obtain the cured thermosetting polyimide resin (cure-CP4).

[0052] Figure 1 This is an infrared spectrum of the thermosetting polyimide (PI) oligomer prepared in Example 1 of this invention before and after curing. As can be seen from the image, the PI oligomer exhibits infrared spectroscopy at 2950 cm⁻¹. -1 The presence of methyl and methylene signals nearby, 1270 cm -1 CNC signal and 2210cm -1 The presence of a carbon-carbon triple bond signal peak initially confirms the successful preparation of PI oligomers; after curing, the carbon-carbon triple bond signal peak completely disappears, indicating complete curing.

[0053] Figure 2 This is the 1H NMR spectrum of the thermosetting polyimide oligomer prepared in Example 1 of this invention. The integral of the corresponding signal peak area is in good agreement with the corresponding number of hydrogen atoms in the PI oligomer, further demonstrating the successful preparation of the PI oligomer.

[0054] Figure 3This is the DSC curve of the thermosetting polyimide oligomer prepared in the embodiments of the present invention. The temperature difference between its melting temperature and curing crosslinking temperature is small, meaning the melt processing window is narrow, making it unsuitable for traditional melt processing techniques. Therefore, the present invention proposes a cold-pressing preforming-re-sintering process, which flexibly solves the processability problem of this type of material.

[0055] Figure 4 These are the thermogravimetric curves of the thermosetting polyimide oligomer prepared in Example 1 of this invention before and after curing. It can be seen that the thermal stability of the resin is significantly improved after curing, with a char residue of over 70% at 800℃.

[0056] Figure 5 This is a cross-sectional SEM image of the thermosetting polyimide resin sample prepared in Example 1 of this invention. Clearly, the PI resin oligomer particles with narrow melt processing windows are not completely melted; the main process involves localized fusion and cross-linking between particles, resulting in a porous morphology and thus making the resin material lightweight.

[0057] Figure 6 This is the DMA curve of the thermosetting polyimide resin prepared in Example 1 of the present invention. The glass transition temperature (Tg) of the thermosetting PI resin (cure-CP4) prepared in Example 1 reached 500°C.

[0058] The prepared thermosetting polyimide resin Cure-CP4 was immersed in lubricating oil (PAO4, polyalphaolefin) in a vacuum oven at 120°C for 48 hours. After cooling to room temperature, the porous resin was removed, and the surface lubricating oil was wiped off for friction testing. Because the thermosetting polyimide resin Cure-CP4 has a porous structure, the purpose of immersion in lubricating oil is to fill the internal pores, so that the oil is squeezed out under pressure during the friction test for lubrication. Figure 7 This is a curve showing the change in the coefficient of friction of the thermosetting polyimide resin sample prepared in Example 1 of this invention under different loads over time after immersion in oil. The coefficient of friction is the ratio of the frictional force between two surfaces to the perpendicular force acting on one of its surfaces, used to describe the frictional conditions at the interface. A stable coefficient of friction indicates, to some extent, good wear resistance of the material. Using an HSR-2M high-speed reciprocating friction testing machine, the oil-absorbing resin sample was rubbed under different loads. It can be seen that the coefficient of friction of the sample is relatively stable during the test and gradually decreases with the increase of load.

[0059] Example 2

[0060] 1) At room temperature, N-methylpyrrolidone (120 g) was added to a clean, dry three-necked flask of 250 mL. Under a nitrogen atmosphere, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (10 g) and 2-(4-amino,2-phenol)-5-aminobenzimidazole (19.34 g) were added separately. After they were completely dissolved, 2,3,3',4'-biphenyltetracarboxylic dianhydride (23.68 g) was added. The reaction was carried out at 0 °C for 5 h. Then 4-phenylethynylphthalic anhydride (24.97 g) was added and the reaction was continued for 5 h for end-capping treatment.

[0061] 2) Add acetic anhydride (32.86 g) and isoquinoline (519.73 mg) to the reaction flask and stir at room temperature for 15 h. Pour the mixture into 1000 mL of methanol to precipitate, wash repeatedly with methanol and filter, and finally dry the filter cake under vacuum at 190 °C for 4 h to obtain yellow thermosetting polyimide oligomer.

[0062]

[0063] 3) Subsequently, the oligomer was pulverized and sieved through a 500-mesh sieve. The resulting powder was placed into a cold-pressing mold cavity and pressed for 10 minutes at a pressure of 20 MPa using a press. The cold-pressed block was then cured in a vacuum oven using a curing process of 240℃-1h and 350℃-2h to finally obtain the cured thermosetting polyimide resin (denoted as Cure-C-CP4).

[0064] Following the same testing method as in Example 1, the Tg of the thermosetting PI resin (cure-C-CP4) prepared in Example 2 also reached 500℃. Figure 6 The char residue at 800°C is over 70%, and the overall performance is similar to that of the resin prepared in Example 1.

[0065] Example 3

[0066] 1) At room temperature, N,N-dimethylacetamide (150g) was added to a clean, dry three-necked flask of 250mL. Under nitrogen atmosphere, bis(4-aminophenyl)tetramethyldisiloxane (7g) and 2-(4-aminophenyl)-5-aminobenzoxazole (9.96g) were added respectively. After they were completely dissolved, pyromellitic dianhydride (9.65g) was added. The reaction was carried out at room temperature for 3h. Then 4-phenylethynylphthalic anhydride (11g) was added and the reaction was continued for 5h for end-capping treatment.

[0067] 2) Add acetic anhydride (11.29 g) and isoquinoline (142.81 mg) to the reaction flask and stir at 60 °C for 12 h. Pour the mixture into 1000 mL of methanol to precipitate the product. After washing with methanol several times and filtering, the filter cake is dried under vacuum at 190 °C for 3 h to obtain a yellow thermosetting polyimide oligomer.

[0068]

[0069] 3) Subsequently, the oligomer was pulverized and sieved through a 250-mesh sieve. The resulting powder was placed into a cold-pressing mold cavity and pressed for 10 minutes at a pressure of 2 MPa using a press. The cold-pressed block was then cured in a vacuum oven using a curing process of 270℃-1h and 380℃-3h to finally obtain the cured thermosetting polyimide resin.

[0070] Using the same testing method as in Example 1, the thermosetting PI resin prepared in Example 3 also achieved a Tg of 500°C and a char residue of over 70% at 800°C, exhibiting overall performance similar to the resin prepared in Example 1.

[0071] Example 4

[0072] 1) At room temperature, N,N-dimethylacetamide (160g) was added to a clean, dry three-necked flask of 250mL. Under a nitrogen atmosphere, bis(3-aminophenyl)tetramethyldisiloxane (8g) and 2-2-(4-aminophenyl)-5-aminopyridineimidazole (PYABZ) (11.39g) were added respectively. After they were completely dissolved, 2,3,3',4'-biphenyltetracarboxylic dianhydride (14.87g) was added. The reaction was carried out at room temperature for 4h. Then 4-phenylethynylphthalic anhydride (13g) was added and the reaction was continued for 4h for end-capping treatment.

[0073] 2) Add acetic anhydride (25.80 g) and isoquinoline (326.42 mg) to the reaction flask and stir at room temperature for 12 h. Pour the mixture into 1000 mL of methanol to precipitate the product. After washing with methanol several times and filtering, the filter cake is dried under vacuum at 190 °C for 3 h to obtain a yellow thermosetting polyimide oligomer.

[0074]

[0075] 3) Subsequently, the oligomer was pulverized and sieved through a 500-mesh sieve. The resulting powder was placed into a cold-pressing mold cavity and pressed for 30 minutes at a pressure of 5 MPa using a press. The cold-pressed block was then cured in a vacuum oven using a curing process of 250℃-2h and 380℃-2h to finally obtain the cured thermosetting polyimide resin.

[0076] Using the same testing method as in Example 1, the thermosetting PI resin prepared in Example 4 also achieved a Tg of 500°C and a char residue of over 70% at 800°C, exhibiting overall performance similar to the resin prepared in Example 1.

[0077] Example 5

[0078] 1) At room temperature, N,N-dimethylacetamide (120g) was added to a clean, dry three-necked flask of 250mL. Under a nitrogen atmosphere, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (6g) and 2-(4-aminophenyl)-5-aminobenzimidazole (10.83g) were added respectively. After they were completely dissolved, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (14.21g) was added. The reaction was carried out at 20℃ for 3h. Then 4-phenylethynylphthalic anhydride (14.98g) was added and the reaction was continued for 5h for end-capping treatment.

[0079] 2) Add acetic anhydride (12.32 g) and isoquinoline (155.92 mg) to the reaction flask and stir at 50 °C for 12 h. Pour the mixture into 1000 mL of methanol to precipitate, wash repeatedly with ethanol and filter. Finally, dry the filter cake under vacuum at 200 °C for 3 h to obtain a yellow thermosetting polyimide oligomer.

[0080]

[0081] 3) Subsequently, the oligomer was pulverized and sieved through a 200-mesh sieve. The resulting powder was placed into a cold-pressing mold cavity and pressed for 30 minutes at a pressure of 10 MPa using a press. The cold-pressed block was then cured in a vacuum oven using a curing process of 250℃-1h and 360℃-3h to finally obtain the cured thermosetting polyimide resin.

[0082] Using the same testing method as in Example 1, the thermosetting PI resin prepared in Example 5 also achieved a Tg of 500°C and a char residue of over 70% at 800°C, exhibiting overall performance similar to the resin prepared in Example 1.

[0083] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a high heat-resistant thermosetting polyimide resin, characterized in that, The general formula of the oligomer of the thermosetting polyimide resin is shown in formula (1): （1） Where n = 1-20, and Ar is selected from any of the following structures: ； Rx represents an aromatic heterocyclic diamine fragment and a siloxane-containing diamine fragment, and the molar ratio of the aromatic heterocyclic diamine fragment and the siloxane-containing diamine fragment in formula (1) is (99 - 1):1; The aromatic heterocyclic diamine fragment is selected from any of the following structures: ； The diamine fragment containing the siloxane structure is selected from any of the following structures: ； The preparation method of the aforementioned high heat-resistant thermosetting polyimide resin specifically includes: S1. Aromatic dianhydride, aromatic heterocyclic diamine, diamine containing siloxane structure, and 4-phenylethynyl phthalic anhydride are mixed in an organic solvent and subjected to polycondensation reaction at 0-50 °C to obtain a polyamic acid solution. S2. Polyamic acid solution is prepared into polyimide oligomer solution by chemical imidization, and then washed, filtered and dried to obtain thermosetting polyimide oligomer powder. S3. The thermosetting polyimide oligomer powder is cold-pressed into shape and then heat-sintered and cured to obtain a cured resin. Step S3 specifically includes: First, the thermosetting polyimide oligomer powder is sieved through a 100-1000 mesh screen, then pressed at 0.1-100MPa for 1 min-3 h to form the product. Finally, it is heated to 350-450 ℃ for heat sintering and curing for 0.5-10 h, and then cooled to room temperature to obtain a high heat-resistant thermosetting polyimide resin.

2. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The aromatic dianhydride includes at least one of pyromellitic dianhydride, 3,3,4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxobisphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, hexafluorodianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride).

3. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The aromatic heterocyclic diamine includes at least one of 2-(4-aminophenyl)-5-aminobenzimidazole, 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-amino,2-phenolyl)-5-aminobenzimidazole, 2-(4-amino,2-phenolyl)-5-aminopyridinibimazole, 2-(4-aminophenyl)-5-aminopyridinibimazole, bis(2-hydroxy-4-aminophenyl)-1,4-phenylenepyridinibimazole, bis(2-hydroxy-4-aminophenyl)-1,4-phenylenebenzodioxazole, and 5-amino-2-(2-hydroxy-4-aminophenyl)-benzoxazole.

4. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The diamine containing a siloxane structure includes at least one of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, bis(4-aminophenyl)tetramethyldisiloxane, bis(3-aminophenyl)tetramethyldisiloxane, bis(4-aminophenyl)-1,3-dimethyl-1,3-diphenyldisiloxane, bis(4-aminophenoxy)dimethylsilane, and bis(4-aminophenoxy)methylphenylsilane.

5. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The solid content of the polyamic acid solution is 10-50 wt%.

6. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The molar ratio of acid anhydride to amino group is 1.01 - 3:1, based on the total amount of acid anhydride contained in aromatic dianhydride and 4-phenylethynylphthalic anhydride, and the total amount of amino group contained in aromatic heterocyclic diamine and siloxane-containing diamine.

7. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, The chemical imidization method includes: A polyimide oligomer solution is prepared by adding a dehydrating agent and a dehydration catalyst to a polyamic acid solution and stirring at room temperature to 150 °C for 2-48 h; wherein the dehydrating agent is at least one of acetic anhydride, propionic anhydride, butyric anhydride, and sodium acetate, and the dehydration catalyst is at least one of triethylamine, isoquinoline, pyridine, and N-methylpyridine.

8. The method for preparing the high heat-resistant thermosetting polyimide resin according to claim 1, characterized in that, Based on the total amount of acid anhydrides contained in aromatic dianhydrides and 4-phenylethynylphthalic anhydrides, the molar ratio of dehydrating agent to acid anhydride is 1-10:1; the molar ratio of dehydrating catalyst to acid anhydride is 0.001-5:1.

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