Low-temperature curing polyimide precursor solution and preparation method thereof

Abstract

The invention relates to a low-temperature curing polyimide precursor solution and a preparation method thereof. The method comprises the following steps: carrying out condensation polymerization reaction on a dianhydride monomer and a diamine monomer in a reaction solvent to obtain a polyamide acid solution; and adding an amino compound containing one or more special functional groups of pyridine, imidazole, quinoline, pyrimidine and azine into the polyamide acid solution, and fully stirring to enable amino in the compound to fully react with carboxyl in a polyamide acid molecular chain, thereby obtaining the polyimide precursor solution capable of being cured at low temperature. According to the preparation method, the curing temperature of polyimide can be greatly reduced, meanwhile, the mechanical property of the material can be improved, the thermal expansion coefficient can be reduced, and the preparation method can be used for preparing polyimide binders, photoresist, electronic packaging, resin, films, fibers and aerogel.

Description

Technical Field

[0001] The invention belongs to the field of material science and technology, and specifically relates to a low-temperature curing polyimide precursor solution and a preparation method thereof. Background Art

[0002] Polyimide is a kind of high-performance polymer containing imide rings in the main chain of the molecule. It is widely used in aviation, aerospace, microelectronics, rail transportation and nuclear industry due to its excellent thermomechanical properties, radiation resistance, low thermal expansion coefficient and electrical insulation. At present, the commonly used curing methods of polyimide are divided into chemical imidization and thermal imidization. Toxic solvents such as pyridine are used in the chemical imidization process, which is not conducive to environmental protection; thermal imidization generally requires high-temperature treatment above 300°C, which will cause the color of the polyimide material to deepen. At the same time, high-temperature treatment will also cause the attached material to warp and even decompose. Therefore, it is particularly important to explore the low-temperature curing of polyimide, especially in the application fields of adhesives, electronic packaging and photoresists.

[0003] Patent CN 110713598 A discloses a method for preparing a soluble low-temperature imidization polyimide. The method uses acetic anhydride and propionic anhydride as dehydrating agents. The low-temperature imidization of polyamic acid can be completed by stirring the reaction at 20-80°C for 1-480 minutes. However, a large amount of dehydrating agent is used during the reaction, and the dehydrating agent is a controlled drug that is easily manufactured.

[0004] Patent CN 114957662 A discloses a low-temperature curing negative photosensitive polyimide composition and a preparation method thereof, which uses a pyridine or imidazole structure capping agent to cap the polyamic acid salt, and dopes with a low-temperature curing catalyst to achieve curing below 200°C. However, considering the limitation of molecular weight, the amount of the capping agent is relatively small, and the synergistic small molecule curing catalysts such as ethylamine, pyridine, picoline, quinoline, isoquinoline, etc. are difficult to completely remove during the low-temperature curing process, which will affect the material performance during the later use.

[0005] Patent CN 117487162 A discloses a low-temperature curable polyimide precursor and a preparation method thereof. The method can achieve low-temperature curing at 180-240°C by combining molecular main chain structure design with a dehydrating agent and a catalyst. However, the dosage and toxicity of the small molecule dehydrating agent and catalyst are relatively large, reaching 200%-400% of the total molar number of the dianhydride monomer respectively.

[0006] Although there are some research and development on low-temperature curing polyimide materials in the prior art, there are some problems with the above invention method. The method of reducing the curing temperature of polyimide in the prior art is usually to add curing catalysts such as p-hydroxybenzoic acid, quinoline, benzimidazole, benzotriazole, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, etc., which can reduce the curing temperature of polyamic acid solution to about 200°C. However, this type of curing catalyst is generally used in large amounts and has a high boiling point. It is only dispersed in the polyamic acid solution through simple physical blending. It is difficult to completely remove it during the low-temperature curing process, which affects the product's later performance. Therefore, it is urgent to develop a preparation method for low-temperature curable polyimide, which can reduce its curing temperature while eliminating the influence of residual small molecule curing catalysts on the later performance of the material. Summary of the invention

[0007] The purpose of the present invention is to overcome the problem that small molecule curing catalysts in the existing polyimide low-temperature curing technology are difficult to completely remove during the low-temperature heat treatment process, thereby affecting the later use performance of the material, and provide a preparation method for a low-temperature curable polyimide precursor solution. In the preparation method, a special group that plays a curing catalytic role is connected to the polyamic acid molecular chain through an amide bond, and low-temperature curing of no higher than 150°C can be achieved.

[0008] To achieve the above object, the present invention discloses a low-temperature curable polyamic acid solution and a preparation method thereof, comprising the following steps:

[0009] (1) adding a diamine monomer and a dianhydride monomer into a reaction solvent and stirring them sufficiently to cause a condensation polymerization reaction to obtain a polyamic acid solution;

[0010] (2) adding an amino compound containing a special functional group into the polyamic acid solution in a certain ratio, and continuing to stir so that the amino group in the compound reacts fully with the carboxyl group in the polyamic acid molecular chain to obtain the low-temperature curable polyimide precursor solution.

[0011] Preferably, the solid content of the polyamic acid solution in step (1) is 1%-40%; and the molar ratio of the dianhydride monomer to the diamine monomer is 0.98:1-1.02:1.

[0012] Preferably, the dianhydride monomer in step (1) is any one or more of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 2,3',3,4'-biphenyl tetracarboxylic dianhydride, bisphenol A dianhydride, 4,4'-oxydiphthalic anhydride, hexafluoroisopropylene phthalic acid, diphenyl sulfide tetracarboxylic dianhydride and 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride. The diamine monomer is a mixture of one or more of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 2-(4-aminophenyl)-5-aminobenzimidazole, 4,4'-diaminodiphenyl sulfone, and 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl in any proportion; and the reaction solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-vinyl pyrrolidone and dimethyl sulfoxide.

[0013] Preferably, the amino compound containing a special functional group in step (2) is 2-amino-5-ethylpyrazine, 1-aminophthalazine, 2-amino-3,6-dimethylpyrazine, 3-aminopyrazine-2-carboxaldehyde, 2-ethyl-3-aminopyrazine, [1,2,4]triazolo[1,5-a][1,3,5]triazine-7-amine, [1,2,4]triazolo[1,5-a]pyrazine-2-amine, 7-(2-pyridyl)[1,2,4]triazolo[1,5-a]pyrimidin-2-amine, 5-methyl[1,2,4]triazolo[1,5-a]pyrimidin-7-amine, 2-aminoquinoline, 3-aminoquinoline, 4-aminoquinoline, 5-aminoquinoline, 6-aminoquinoline, 7-aminoquinoline, 8-aminoquinoline, 5-aminobenzimidazole, 2-aminoimidazole, 5-aminoimidazole-4-carboxamide, 7-aminoimidazole [1,2-c] pyrimidine, imidazo [1,2-a] pyridin-6-amine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, aminopyrazine, 2,3-diaminopyridine, 2,4-diaminopyridine, 2,5-diaminopyridine, 3,4-diaminopyridine, 5,6-diaminobenzimidazolone, 5-amino-2-(4-aminophenyl)benzimidazole, 2,6-diaminopyrazine, 4,5-diaminopyridazine, 3,6-diaminopyridazine, 2,4-diamino-1,3,5-triaminopyridine 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine, 2,4-diamino-6-[2-(2-undecyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2,4-diamino-6-butylamino-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2-vinyl-4,6-diamino-1,3,5-triazine, 2,4-diamino-6-diethylamino-1,3,5-triazine, 2,4-amino-6-methoxy-1,3,5-triazine, 2-chloro-4,6-di One or more of amino-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-amino-6-(3-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-diallylamino-1,3,5-triazine, 2,4-amino-6-(4-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-[4-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine and 2,4,6-triamino-1,3,5-triazine are mixed in any proportion.

[0014] Preferably, the molar ratio of the amino compound containing a special functional group to the dianhydride monomer in step (2) is 0.01:1-2:1.

[0015] Another object of the present invention is to provide a low-temperature curable polyimide precursor solution prepared by the above method and a polyimide prepared based on the solution. Preferably, the solid content of the solution is 1%-60%, the curing temperature is not higher than 150°C, and the curing time is 1-120min.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) Compared with the method of adding a small molecule curing catalyst by physical blending, the method of the present invention connects the special functional group that plays a curing catalytic role to the polyimide molecular chain through an amide bond, avoiding the problem that the small molecule curing catalyst is difficult to completely remove during the low-temperature curing process, which affects the performance of the material in the later stage. At the same time, the formation of the amide bond increases the cross-linking and entanglement between the polyimide molecular chains, which is beneficial to improving the mechanical properties of the material and reducing the thermal expansion coefficient;

[0018] (2) Compared with the method of capping the polyamic acid molecular chain with a capping agent containing a curing catalyst structure, the method of the present invention has no special requirements on the molecular weight of the polyamic acid, and can connect more groups that play a curing catalytic role in the polyamic acid molecular chain through chemical bonds. It does not need to be used in combination with a small molecule curing catalyst to achieve the effect of low-temperature curing.

[0019] (3) The method of the present invention is to react the amino group in the amino compound containing special functional groups with the carboxyl group in the polyamic acid molecular chain to form an amide bond. There are no special requirements for the main chain structure of the polyamic acid molecule and the reactivity of the raw materials dianhydride and diamine. The reaction conditions are mild and there is no need to change the existing synthesis and processing equipment, which is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Comparison of the imidization degree of the films prepared in Example 3 of the present invention and Comparative Example 1 under different curing conditions

[0021] Figure 2 Stress-strain curves of the films prepared in Example 3 of the present invention and Comparative Example 1 under different curing conditions

[0022] Figure 3 The deformation curves of the films prepared in Example 3 and Comparative Example 1 under different curing conditions are as a function of temperature. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] In the description of this specification, the description with reference to the terms "one embodiment", "another embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0025] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0026] The present invention provides the following specific embodiments and comparative examples to further illustrate the scheme of the present invention.

[0027] Example 1

[0028] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0029] (2) 0.368 g (0.00168 mol) of 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine was added to the above polyamic acid solution, and the reaction was continued for 5 hours at room temperature until the solution became clear and the viscosity no longer changed, thereby obtaining a low-temperature curable polyimide precursor solution.

[0030] Example 2

[0031] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0032] (2) 0.737 g (0.00336 mol) of 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine was added to the above polyamic acid solution, and the reaction was continued at room temperature for 5 hours until the solution became clear and the viscosity no longer changed, thereby obtaining a low-temperature curable polyimide precursor solution.

[0033] Example 3

[0034] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0035] (2) 1.104 g (0.00504 mol) of 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine was added to the polyamic acid solution, and the reaction was continued at room temperature for 5 hours until the solution became clear and the viscosity no longer changed, thereby obtaining a low-temperature curable polyimide precursor solution.

[0036] Example 4

[0037] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0038] (2) 0.686 g (0.00504 mol) of [1,2,4]triazolo[1,5-a][1,3,5]triazine-7-amine was added to the polyamic acid solution, and the reaction was continued for 5 h at room temperature until the solution became clear and the viscosity no longer changed, thereby obtaining a low-temperature curable polyimide precursor solution.

[0039] Example 5

[0040] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0041] (2) 0.555 g (0.00504 mol) of 3,6-diaminopyridazine was added to the polyamic acid solution, and the reaction was continued at room temperature for 5 h until the solution became clear and the viscosity did not change, thereby obtaining a low-temperature curable polyimide precursor solution.

[0042] Example 6

[0043] (1) 3.070 g (0.0153 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 3.346 g (0.0153 mol) of pyromellitic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 12 wt %;

[0044] (2) 1.006 g (0.00459 mol) of 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine was added to the above polyamic acid solution, and the reaction was continued at room temperature for 5 hours until the solution became clear and the viscosity no longer changed, thereby obtaining a low-temperature curable polyimide precursor solution.

[0045] Comparative Example 1

[0046] 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 hours in an ice-water bath (0°C) to obtain a polyamic acid solution with a solid content of 15 wt%;

[0047] Comparative Example 2

[0048] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0049] (2) 2.167 g (0.0168 mol) of a small molecule curing catalyst quinoline was added to the polyamic acid solution, and the mixture was stirred for 5 h at room temperature to obtain a low-temperature curable polyimide precursor solution.

[0050] Comparative Example 3

[0051] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.941 g (0.0168 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0052] (2) 1.982 g (0.0168 mol) of a small molecule curing catalyst benzimidazole was added to the polyamic acid solution, and the mixture was stirred for 5 h at room temperature to obtain a low-temperature curable polyimide precursor solution.

[0053] Comparative Example 4

[0054] (1) 3.362 g (0.0168 mol) of 4,4'-diaminodiphenyl ether was dissolved in 50 mL of N,N-dimethylacetamide solvent. After the 4,4'-diaminodiphenyl ether was completely dissolved, 4.907 g (0.0167 mol) of 3,3',4,4'-biphenyltetracarboxylic anhydride was added to the above system in batches. The reaction was continued for 5 h in an ice-water bath (0° C.) to obtain a polyamic acid solution with a solid content of 15 wt %;

[0055] (2) 0.013 g (0.0002 mol) of a capping agent 5-aminobenzimidazole was added to the polyamic acid solution, and the reaction was continued at room temperature for 5 hours to obtain a low-temperature curable polyimide precursor solution.

[0056] The following only takes the film as an example to examine the performance difference between the embodiment and the comparative example, but the application scope of the low-temperature curable polyimide precursor solution prepared by the method of the present invention is not limited to the film, and can also be used for the preparation of polyimide adhesives, photoresists, electronic packaging, resins, fibers and aerogels. The prepared polyimide precursor solution is coated on a glass plate with a thickness of about 30 μm, heated in an oven at 60°C for 2 hours to remove the solvent, and then heated to a specified temperature for 1 hour for curing, to obtain the polyimide film required for the test.

[0057] The degree of imidization was calculated by the following formula:

[0058]

[0059] Wherein, S represents the area of ​​the corresponding characteristic peak in the infrared spectrum, and p and c represent the partially imidized and fully imidized samples, respectively.

[0060] The mechanical properties were measured using a universal material testing machine. The sample shape was a dumbbell-shaped spline (length × width of the middle stress area = 20 × 4 mm). The sample thickness was measured using a digital vertical optical meter. The tensile rate was 10 mm / min, and the measurement was repeated for 5 groups of splines to take the average value.

[0061] The thermal expansion coefficient of the film was tested using a thermomechanical analyzer (TMA). The temperature was quickly raised to 230°C in a nitrogen atmosphere and then cooled at 5°C / min. The slope of the PI film deformation in the temperature range of 25-200°C during the cooling process was the thermal expansion coefficient of the film.

[0062] The performance comparison of the polyimide films prepared in the comparative example and the example is shown in the following table:

[0063] Table 1 Comparison of properties of polyimide films prepared in comparative examples and examples

[0064]

[0065] It can be seen from Table 1 that the low-temperature curing polyimide precursor solution prepared by the method of the present invention has a higher imidization degree and more excellent mechanical properties under the same curing conditions. Under the curing conditions of heating at 150°C for 1h, the imidization degree of some examples can reach more than 95%, which is almost completely imidized. Figure 1 The change of imidization degree with temperature shows that compared with the comparative example 1 without adding curing catalyst, the imidization degree of the low-temperature curing polyimide precursor solution prepared by the method of the present invention reaches more than 50% when heated at 100°C for 1 hour, and almost completely imidized when heated at 150°C for 1 hour, indicating that the method of the present invention can achieve the effect of low-temperature curing of polyimide. Figure 2 , Attachment Figure 3The test results of mechanical properties and coefficient of thermal expansion (CTE) show that the film prepared by the low-temperature curing polyimide precursor solution described in the method of the present invention and heated at 200°C for 1 hour has better mechanical properties and lower coefficient of thermal expansion than the film prepared in Comparative Example 1 and heated at 300°C for 1 hour. This is mainly due to the formation of amide bonds between the amino compound containing special functional groups and the polyamic acid molecular chain, which increases the crosslinking and entanglement between the polyimide molecular chains.

[0066] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a low-temperature curing polyimide precursor solution, comprising the following steps: (1) adding a diamine monomer and a dianhydride monomer into a reaction solvent and stirring them sufficiently to cause a condensation polymerization reaction to obtain a polyamic acid solution; (2) adding an amino compound containing a special functional group into the polyamic acid solution in a certain ratio, and continuing to stir so that the amino group in the compound reacts fully with the carboxyl group in the polyamic acid molecular chain to obtain the low-temperature curable polyimide precursor solution.

2. The method according to claim 1, characterized in that: The solid content of the polyamic acid solution in step (1) is 1%-40%; the molar ratio of the dianhydride monomer to the diamine monomer is 0.98:1-1.02:

1.

3. The method according to claim 1, characterized in that: The dianhydride monomer in step (1) is any ratio of one or more of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 2,3',3,4'-biphenyl tetracarboxylic dianhydride, bisphenol A dianhydride, 4,4'-oxydiphthalic anhydride, hexafluoroisopropylene phthalic acid, diphenyl sulfide tetracarboxylic dianhydride and 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride The diamine monomer is a mixture of one or more of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 2-(4-aminophenyl)-5-aminobenzimidazole, 4,4'-diaminodiphenyl sulfone, and 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl in any proportion; and the reaction solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-vinylpyrrolidone and dimethyl sulfoxide.

4. The method according to claim 1, characterized in that: The amino compound containing a special functional group in step (2) is 2-amino-5-ethylpyrazine, 1-aminophthalazine, 2-amino-3,6-dimethylpyrazine, 3-aminopyrazine-2-carboxaldehyde, 2-ethyl-3-aminopyrazine, [1,2,4]triazolo[1,5-a][1,3,5]triazine-7-amine, [1,2,4]triazolo[1,5-a]pyrazine-2-amine, 7-(2-pyridyl)[1,2,4]triazolo[1,5-a]pyrimidin-2-amine, 5-methyl[1,2,4]triazolo[1,5-a]pyrimidin-7-amine, 2-aminoquinoline, 3-aminoquinoline, 4-aminoquinoline, 5-aminoquinoline, 6-aminoquinoline, Quinoline, 7-aminoquinoline, 8-aminoquinoline, 5-aminobenzimidazole, 2-aminoimidazole, 5-aminoimidazole-4-carboxamide, 7-aminoimidazole [1,2-c] pyrimidine, imidazo [1,2-a] pyridin-6-amine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, aminopyrazine, 2,3-diaminopyridine, 2,4-diaminopyridine, 2,5-diaminopyridine, 3,4-diaminopyridine, 5,6-diaminobenzimidazolone, 5-amino-2-(4-aminophenyl)benzimidazole, 2,6-diaminopyrazine, 4,5-diaminopyridazine, 3,6-diaminopyridazine, 2,4-diamino-1,3,5-triazine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-thiazine, 2,4-diamino-6-[2-(2-undecyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2,4-diamino-6-butylamino-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2-vinyl-4,6-diamino-1,3,5-triazine, 2,4-diamino-6-diethylamino-1,3,5-triazine, 2,4-amino-6-methoxy-1,3,5-triazine, 2-chloro-4,6-diamino The present invention can be used as a mixture of one or more of 1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-amino-6-(3-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-diallylamino-1,3,5-triazine, 2,4-amino-6-(4-fluorophenyl)-1,3,5-triazine, 2,4-diamino-6-[4-(trifluoromethyl)phenyl]-1,3,5-triazine, 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine and 2,4,6-triamino-1,3,5-triazine in any proportion.

5. The method according to claim 1, characterized in that In step (2), the molar ratio of the amino compound containing a special functional group to the dianhydride monomer is 0.01:1-2:

1.

6. A low-temperature curable polyimide precursor solution prepared by the method according to any one of claims 1 to 5 and a polyimide prepared based on the solution, characterized in that: The solid content of the solution is 1%-60%, the curing temperature is not higher than 150° C., and the curing time is 1-120 minutes.

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