Polyimide polymer, preparation method, polyimide film and application

Abstract

The invention discloses a polyimide polymer, a preparation method, a polyimide film and application. The polyimide polymer has a structure as shown in a formula I: # imgabs0 #. The polyimide film formed by the polyimide polymer has high transparency and low dielectric constant; meanwhile, the excellent thermal property and mechanical property of the polyimide film are also maintained. Wide application prospects are realized in the fields of liquid crystal display materials, integrated circuits and micro-electronics.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyimide polymer and a preparation method thereof, a polyimide film and applications thereof. Background Art

[0002] Polyimide (PI) film has excellent thermal stability, chemical resistance, good mechanical properties and electrical properties. It is an important polymer in advanced liquid crystal display technology, integrated circuits and microelectronics industries. With the rapid development of the above technologies, higher requirements are placed on the performance of PI films. For example, the development of 5G communication technology has put forward the demand for PI materials with lower dielectric constants. The field of liquid crystal displays requires that the PI orientation film has a stable pre-tilt angle for liquid crystal molecules, and also has high temperature resistance and good transparency. High-frequency and high-speed ultra-large-scale integrated circuits require PI films to have lower dielectric constants and dielectric losses to reduce signal transmission delays and crosstalk, and achieve efficient signal transmission. Optoelectronic devices require PI films to have excellent heat resistance and low expansion coefficients to meet the requirements of electrode deposition and annealing during processing.

[0003] Traditional PI films usually exhibit high dielectric constant, low transparency and poor solubility in organic solvents due to their electronic conjugated structure and the formation of intramolecular and intermolecular charge transfer complexes (CTCs), and cannot meet the above industrial requirements.

[0004] Therefore, it is crucial to develop a PI film that is simultaneously highly transparent, heat-resistant, high in mechanical properties, low in dielectricity, and soluble. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the first aspect of the present invention provides a polyimide polymer. The polyimide film formed by the polyimide polymer has high transparency and low dielectric constant; at the same time, the excellent thermal and mechanical properties of the polyimide film are maintained.

[0006] The second aspect of the present invention also provides a method for preparing a polyimide polymer.

[0007] The third aspect of the present invention also provides a polyimide film.

[0008] The fourth aspect of the present invention also provides a method for preparing a polyimide film.

[0009] The fifth aspect of the present invention also provides an application of the polyimide film.

[0010] The polyimide polymer provided according to the first aspect of the present invention has a structure shown in Formula I:

[0011]

[0012] Wherein, m and n are each independently selected from any integer from 10 to 100;

[0013] R 1 Selected from H, C 1～3 The alkyl group;

[0014] R 2 Selected from

[0015] R 3 Selected from Wherein, X is selected from any integer of 0 to 15.

[0016] The polyimide polymer according to the embodiment of the present invention has at least the following beneficial effects:

[0017] An alkyl chain is introduced into the structural formula of the polyimide (PI) polymer of the present invention. Due to the presence of a rigid benzimidazole structure in the PI main chain, the PI has excellent thermal and mechanical properties. On the other hand, thanks to the introduction of the alkyl chain and the presence of a bulky fluorene-based Cardo structure, the packing density and main chain orientation of the molecular chain and the formation of charge transfer complexes (CTCs) can be significantly reduced, so that the dielectric constant, light transmittance and solubility of the PI film are improved, and the PI film has a wide range of application prospects in the fields of liquid crystal display, integrated circuits and microelectronics.

[0018] According to a preferred embodiment of the present invention, m and n are independently selected from any integer from 10 to 100, for example, 10, 20, 30, 40, 50, 60, 80, 90, 100 or a subrange consisting of any two values.

[0019] According to a preferred embodiment of the present invention, the R 3 Selected from

[0020] At least one of .

[0021] According to a preferred embodiment of the present invention, the polyimide polymer is selected from at least one of the following structural formulas:

[0022]

[0023]

[0024] Here, m and n are each independently selected from any integer of 10 to 100.

[0025] The method for preparing a polyimide polymer according to the second aspect of the present invention comprises the following steps:

[0026] S1, in an inert atmosphere, diamine monomer 1, diamine monomer 2, a catalyst, an aromatic dianhydride monomer and a first strong polar solvent are mixed to carry out reaction I, and the temperature is raised to 100-180° C. to continue reaction II to obtain a first reaction solution;

[0027] S2, adding the first reaction solution dropwise into an alcohol solvent to generate a precipitate to obtain an intermediate;

[0028] S3, under an inert atmosphere, mixing the intermediate, R3-OR3, triethylamine and a second strong polar solvent to carry out reaction III to obtain a second reaction solution;

[0029] S4, adding the second reaction solution dropwise into an alcohol solvent to generate precipitation, thereby obtaining the polyimide polymer;

[0030] The aromatic dianhydride monomer is selected from one of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 4,4'-(4,4'-isopropyldiphenoxy) diphthalic anhydride or 4,4'-oxydiphthalic anhydride;

[0031] Wherein, the structural formulas of the diamine monomer 1, diamine monomer 2 and the intermediate are as follows:

[0032]

[0033] In the structural formulas of the diamine monomer 1, diamine monomer 2, intermediate, and R3-O--R3, m, n, R 1 , R 2 , R 3 The definitions of m, n, and R are the same as those in the first aspect. 1 , R 2 , R 3 The definitions of correspond to the same.

[0034] According to a preferred embodiment of the present invention, in step S1, the catalyst is selected from at least one of isoquinoline, acetic anhydride, triethylamine or pyridine.

[0035] According to a preferred embodiment of the present invention, in step S1, the molar ratio of the catalyst to the diamine monomer 1 is 0.01-0.1:1.

[0036] According to a preferred embodiment of the present invention, the molar ratio of the diamine monomer 1, the diamine monomer 2 and the aromatic dianhydride monomer is (0.45-0.55):(0.45-0.55):1.

[0037] According to a preferred embodiment of the present invention, the molar ratio of the intermediate, R3-O-R3 and triethylamine is 1:(1-5):(1-5).

[0038] According to a preferred embodiment of the present invention, in steps S2 and S4, the alcohol solvent is independently selected from at least one of methanol, ethanol, propanol or isopropanol.

[0039] According to a preferred embodiment of the present invention, in step S1, the temperature of the reaction I is 20-30°C, for example, 20°C, 25°C or 30°C.

[0040] According to a preferred embodiment of the present invention, in step S1, the reaction time of I is 10 to 25 hours, for example, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 25 hours.

[0041] According to a preferred embodiment of the present invention, in step S1, the time of reaction II is ≥ 3 h.

[0042] According to a preferred embodiment of the present invention, in step S1, the reaction time of II is ≤36h. For example, the reaction time is 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 28h, 30h, 36h, etc.

[0043] According to a preferred embodiment of the present invention, the temperature of the reaction III is 20-30°C, for example, 20°C, 25°C or 30°C.

[0044] According to a preferred embodiment of the present invention, the time of reaction III is 10 to 32 hours, for example, 10 hours, 12 hours, 24 hours, 26 hours, 28 hours, 30 hours, or 32 hours.

[0045] According to a preferred embodiment of the present invention, the polarities of the first strongly polar solvent and the second strongly polar solvent are respectively above 4.0.

[0046] According to a preferred embodiment of the present invention, the first strong polar solvent and the second strong polar solvent are independently selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide and m-methylphenol.

[0047] According to a preferred embodiment of the present invention, in step S2, the amount of ethanol used is 10 to 15 times the volume of the first reaction liquid.

[0048] According to a preferred embodiment of the present invention, in step S4, the amount of ethanol used is 10 to 15 times the volume of the second reaction liquid.

[0049] According to a preferred embodiment of the present invention, the method further comprises: filtering the precipitate obtained in step S2 and performing a first drying treatment to obtain the intermediate.

[0050] According to a preferred embodiment of the present invention, the method further comprises: filtering the precipitate obtained in step S4 and performing a second drying treatment to obtain the polyimide polymer.

[0051] According to a preferred embodiment of the present invention, in step S2 or S4, the conditions of the first drying treatment and the second drying treatment are independently vacuum drying at 80-100° C. for 8-12 hours.

[0052] The third aspect of the present invention provides a polyimide film, wherein the polyimide film comprises the polyimide polymer described in the first aspect of the present invention.

[0053] Therefore, the polyimide film of the present invention has high light transmittance, low dielectric constant, and excellent thermal and mechanical properties.

[0054] A fourth aspect of the present invention provides a method for preparing a polyimide film, comprising the following steps:

[0055] The polyimide polymer described in the first aspect and the third organic solvent are mixed and stirred to obtain a solution A; the solution A is coated on a substrate, evacuated, and subjected to a heating and heat preservation treatment; after the treatment is completed, the solution is cooled, the substrate is peeled off, and dried to obtain the solution.

[0056] The method for preparing the polyimide film according to the embodiment of the present invention has at least the following beneficial effects:

[0057] The raw materials involved in the preparation method of the present invention are easily available and the preparation process is simple and controllable, which is conducive to industrial production. The polyimide film containing alkyl chain fluorene Cardo and benzimidazole structure obtained by the preparation method has high thermal stability and excellent mechanical properties, and its dielectric properties, light transmittance and solubility are improved. The polyimide film prepared by the present invention is suitable for application in the fields of integrated circuits, electronics, microelectronics and liquid crystal displays.

[0058] According to a preferred embodiment of the present invention, the solid content of the solution A is 8-18 wt %.

[0059] According to a preferred embodiment of the present invention, the steps of heating and heat preservation treatment are as follows:

[0060] Keep at 50±2℃ for 8~12 hours, 100±2℃ for 2~4 hours, 150±2℃ for 2~4 hours, and 200±2℃ for 2~4 hours.

[0061] According to a preferred embodiment of the present invention, the substrate is a silica glass plate.

[0062] According to a preferred embodiment of the present invention, the third organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide and N,N-dimethylacetamide.

[0063] A fifth aspect of the present invention provides an application of the polyimide polymer described above; or the polyimide film described above in integrated circuits, electronics, microelectronics and flexible display materials.

[0064] In the present invention Indicates the attachment site of a group.

[0065] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0067] Figure 1 The infrared spectra of the polyimide films prepared in Examples 6 to 10 of the present invention and Comparative Example 1;

[0068] Figure 2 The nuclear magnetic resonance hydrogen spectra of the polyimide films obtained in Comparative Example 1 and Example 8 of the present invention are shown;

[0069] Figure 3 The UV-visible spectra of the polyimide films prepared in Examples 6 to 10 of the present invention and Comparative Example 1;

[0070] Figure 4 The dielectric constant and loss-frequency curves of the polyimide films prepared in Examples 6 to 10 of the present invention and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0071] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0072] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0073] Some of the raw materials in the present invention are as follows:

[0074] Synthesis of diamine monomer 1: The structural formula and preparation method are as follows:

[0075]

[0076] (1) Weigh 0.05 mol of 2,7-dihydroxy-9-fluorenone and add it to a 500 mL single-necked flask, add 0.4 mol of 2,6-dimethylaniline, and then drop 0.025 mol of methanesulfonic acid (CH3SO3H) as a catalyst. Under the protection of nitrogen, heat to 150°C and react for 15 hours. After the reaction, cool the reaction solution to 110°C, add 200 mL of triethylamine, and continue to reflux at 110°C for 20 minutes.

[0077] (2) After stopping the reaction, cool to room temperature, add an appropriate amount of ethanol to precipitate a black viscous solid, let it stand and filter to obtain a crude product, wash the black viscous solid with ethanol several times to a light yellow powder solid, filter and take a solid sample and dry it in a vacuum drying oven at 110° C. for 12 hours to finally obtain 15.61 g of pure diamine monomer 1.

[0078] Example 1

[0079] This example provides a polyimide polymer I-1, whose structural formula and preparation method are as follows:

[0080]

[0081] S1. Place 1.7769g of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 0.8731g of diamine monomer 1 and 0.4485g of diamine monomer 2 in a two-necked flask; pour 14.06mL of N-methylpyrrolidone (NMP) solvent into the two-necked flask, and finally drop 0.13g of isoquinoline. Stir magnetically to mix evenly, react at room temperature for 12 hours under nitrogen protection, then heat to 120°C for 1 hour, and continue to heat to 180°C for 3 hours to obtain the first reaction solution;

[0082] S2, the first reaction solution was added dropwise to 400 mL of ethanol to produce a fibrous precipitate, which was allowed to stand and filtered. The precipitate was vacuum dried at 80° C. for 10 hours to obtain an intermediate;

[0083] S3, taking 1.4773 g of the above intermediate and dissolving it in 30 mL of N,N-dimethylformamide (DMF), adding 0.51 g of acetic anhydride and 0.505 g of triethylamine, reacting for 24 hours under nitrogen protection to obtain a second reaction solution;

[0084] S4. The second reaction solution is added dropwise to 400 mL of ethanol to generate a fibrous precipitate, which is allowed to stand and filtered; the precipitate is vacuum dried at 80° C. for 10 hours to obtain a polyimide polymer.

[0085] The number average molecular weight was measured by GPC method and was 2.62×10 4g·mol -1 , PDI=1.70, and the average number of repeating units m and n are both 17.

[0086] Example 2

[0087] This example provides a polyimide polymer I-2, whose structural formula and preparation method are as follows:

[0088]

[0089] The preparation method is basically the same as that of Example 1, except that 0.51 g of acetic anhydride in step S3 is replaced by 0.791 g of butyric anhydride.

[0090] The number average molecular weight was measured by GPC method and was 3.10×10 4 g·mol -1 , PDI=1.92, and the average number of repeating units m and n are both 19.

[0091] Example 3

[0092] This example provides a polyimide polymer I-3, whose structural formula and preparation method are as follows:

[0093]

[0094] The preparation method is basically the same as that of Example 1, except that 0.51 g of acetic anhydride in step S3 is replaced with 1.072 g of hexanoic anhydride.

[0095] The number average molecular weight was measured by GPC method and was 2.95×10 4 g·mol -1 , PDI=1.94, and the average number of repeating units m and n are both 18.

[0096] Example 4

[0097] This example provides a polyimide polymer I-4, whose structural formula and preparation method are as follows:

[0098]

[0099] The preparation method is basically the same as that of Example 1, except that 0.51 g of acetic anhydride in step S3 is replaced with 1.352 g of octanoic anhydride.

[0100] The number average molecular weight was measured by GPC method and was 3.90×10 4 g·mol -1 , PDI=1.97, and the average number of repeating units m and n are both 23.

[0101] Example 5

[0102] This example provides a polyimide polymer I-5, whose structural formula and preparation method are as follows:

[0103]

[0104] The preparation method is basically the same as that of Example 1, except that 0.51 g of acetic anhydride in step S3 is replaced with 1.633 g of capric anhydride.

[0105] The number average molecular weight was measured by GPC method and was 3.46×10 4 g·mol -1 , PDI=1.99, and the average number of repeating units m and n are both 19.

[0106] Example 6

[0107] This example provides a polyimide film, and the preparation method thereof is as follows:

[0108] The polyimide polymer I-1 prepared in Example 1 of the present invention was dissolved in DMF, and the solid content of the solution was controlled to be 10%. After sufficient stirring and dissolution, it was evenly coated on a clean silica glass plate, vacuumed and allowed to stand for 2 hours, then heated to 50°C and dried for 8 hours, and then kept warm at 100°C, 150°C, and 200°C for 3 hours respectively. After cooling, a highly transparent and low dielectric polyimide film (named: 6FDA-OAc-NH) was obtained.

[0109] Example 7

[0110] This example provides a polyimide film (named: 6FDA-OBu-NH), and its preparation method is the same as the preparation method of Example 6, except that the polyimide polymer I-2 prepared in Example 2 is used to replace the polyimide polymer I-1.

[0111] Example 8

[0112] This example provides a polyimide film (named: 6FDA-OHe-NH), and its preparation method is the same as the preparation method of Example 6, except that the polyimide polymer I-3 prepared in Example 2 is used to replace the polyimide polymer I-1.

[0113] Example 9

[0114] This example provides a polyimide film (named: 6FDA-OOc-NH), and its preparation method is the same as the preparation method of Example 6, except that the polyimide polymer I-4 prepared in Example 2 is used to replace the polyimide polymer I-1.

[0115] Example 10

[0116] This example provides a polyimide film (named: 6FDA-ODe-NH), and its preparation method is the same as the preparation method of Example 6, except that the polyimide polymer I-5 prepared in Example 2 is used to replace the polyimide polymer I-1.

[0117] Comparative Example 1

[0118] Comparative Example 1 provides a polyimide film, the structural formula and preparation method of which are as follows:

[0119]

[0120] S1. Place 1.7769g of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 0.8731g of diamine monomer 1 and 0.4485g of diamine monomer 2 in a two-necked flask; pour 14.06mL of N-methylpyrrolidone (NMP) solvent into the two-necked flask, and finally drop 0.13g of isoquinoline. Stir magnetically to mix evenly, react at room temperature for 12 hours under nitrogen protection, then heat to 120°C for 1 hour, and continue to heat to 180°C for 3 hours to obtain the first reaction solution;

[0121] S2, the first reaction solution was added dropwise to 400 mL of ethanol to generate a fibrous precipitate, which was allowed to stand for filtration and then dried under vacuum at 80° C. for 10 hours to obtain a polyimide resin.

[0122] S3. Take part of the above polyimide resin and dissolve it in DMF, control the solid content to 10%, stir it thoroughly to dissolve, evenly apply it on a clean silica glass plate, evacuate it and let it stand for 2 hours, then heat it to 50°C and dry it for 8 hours, then keep it at 100°C, 150°C and 200°C for 3 hours respectively, and obtain a polyimide film (named: 6FDA-OH-NH) after cooling.

[0123] The number average molecular weight was measured by GPC method and was 2.55×10 4 g·mol -1 , PDI=1.73, and the average number of repeating units m and n are both 17.

[0124] Performance Testing

[0125] Infrared spectrum test: The polyimide films prepared in Examples 6 to 10 of the present invention and Comparative Example 1 were subjected to infrared spectrum test, and the results are as follows: Figure 1 As shown:

[0126] Its structure was confirmed by infrared spectroscopy. The infrared (IR) spectrum of the prepared film product comparative example 1 is shown in Figure 1. The spectrum has a wavelength of 3105-3629 cm -1The broad absorption band is the characteristic absorption peak of -OH and -NH-, 2957-2861cm -1 The CH stretching vibration absorption peak of methyl group, 1776-1785cm -1 and 1708-1726cm -1 The asymmetric and symmetric stretching vibration absorption peaks of C=O in the imide ring are 1608 cm -1 、1596cm -1 and 1484cm -1 Corresponding to the vibration of the aromatic ring skeleton, 1366-1369cm -1 Corresponding to CN stretching vibration.

[0127] The IR spectra of Examples 6 to 10 are shown in Figure 1. Compared with the IR spectrum of Comparative Example 1, the IR spectra of Examples 6 to 10 are 3105-3629 cm -1 The characteristic absorption broad peak intensity weakened, 2957-2861cm -1 The characteristic peak of CH stretching vibration at 1763 cm-1 is enhanced, and the absorption peak of C=O symmetric stretching vibration in the imide ring is blue-shifted. -1 New C=O stretching vibration characteristic peaks appeared on the left and right.

[0128] Furthermore, the polyimide films obtained in Example 8 and Comparative Example 1 of the present invention were dissolved in deuterated DMSO and then subjected to H NMR spectrum testing. The results are as follows: Figure 2 As shown:

[0129] The H NMR spectrum (600 MHz, CD3Cl) of the film product is shown in the attached figure. Figure 2 As shown, for Comparative Example 1, 9.48ppm and 13.28ppm in the figure correspond to the proton signal singlets of -OH and -NH-, respectively, 2.03ppm corresponds to the methyl proton signal singlet, and 6.77-8.35ppm corresponds to the aromatic proton signal peak. Compared with the H NMR spectrum of Comparative Example 1, the -OH proton signal singlet at 9.48ppm in Example 8 disappears, and three new signal peaks appear in the aliphatic region, namely 2.56ppm (H2), 1.66ppm (H3) and 0.95ppm (H4), which correspond to -OCO-CH2-, -CH2- and -CH3 of the butyryloxy group in Example 8, respectively.

[0130] The polyimide films obtained in the above-mentioned Examples 6 to 10 and Comparative Example 1 were subjected to the following performance tests. The results are shown in Tables 1 and 2.

[0131] Glass transition temperature (T g ): The temperature was measured by differential scanning calorimetry (DSC) under nitrogen protection at a heating rate of 10°C / min. The results are shown in Table 1.

[0132] Tensile strength (T s ): The tensile properties of the polyimide film were tested at a tensile rate of 5 mm / min at room temperature using an electronic universal testing machine. The tensile load was 1000 N. Each sample was tested 5 times in parallel and the average value was taken. The results are shown in Table 1.

[0133] Transmittance (T 450 ): The transmittance of the film (thickness of the film is 25±2μm) at 450nm was measured using a UV-visible spectrophotometer. The results are as follows Figure 3 And as shown in Table 1.

[0134] Dielectric constant (D k ), dielectric loss (D f ): The dielectric constant and dielectric loss of polyimide film at 1MHz were measured using the capacitance test method. The results are as follows Figure 4 And as shown in Table 1.

[0135] Solubility: Take 10 mg of the film sample and dissolve it in 1 mL of solvent. Place it in a sealed container at room temperature for 24 hours and observe the dissolution of the film. If it cannot be dissolved, heat it to the boiling point of the solvent and observe whether the film dissolves: ++, soluble at room temperature; +, soluble when heated; ±, partially dissolved or expanded when heated; -, insoluble even when heated. The results are shown in Table 2.

[0136] Table 1: Performance test results of polyimide films obtained in Examples 6 to 10 and Comparative Example 1

[0137]

[0138] Table 2: Solubility test results of polyimide films obtained in Examples 6 to 10 and Comparative Example 1

[0139]

[0140]

[0141] It can be seen from the above test results that the polyimide film prepared by the preparation method provided by the present invention has a lower dielectric constant and a higher light transmittance, while also maintaining the excellent thermal properties, mechanical properties and solubility properties of the polyimide film, and is suitable for integrated circuits, electronics, microelectronics, liquid crystal displays and other fields.

[0142] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A polyimide polymer, characterized in that It has the structure shown in Formula I: Wherein, m and n are each independently selected from any integer from 10 to 100; R 1 Selected from H, C 1～3 The alkyl group; R 2 Selected from R 3 Selected from Wherein, X is selected from any integer of 0 to 15.

2. The polyimide polymer according to claim 1, characterized in that R 3 Selected from At least one of .

3. The polyimide polymer according to claim 1 or 2, characterized in that: The polyimide polymer is selected from at least one of the following structural formulas: Here, m and n are each independently selected from any integer of 10 to 100.

4. A method for preparing a polyimide polymer as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1, in an inert atmosphere, diamine monomer 1, diamine monomer 2, a catalyst, an aromatic dianhydride monomer and a first strong polar solvent are mixed to carry out reaction I, and the temperature is raised to 100-180° C. to continue reaction II to obtain a first reaction solution; S2, adding the first reaction solution dropwise into an alcohol solvent to generate a precipitate to obtain an intermediate; S3, under an inert atmosphere, mixing the intermediate, R3-O-R3, triethylamine and a second strong polar solvent to carry out reaction III to obtain a second reaction solution; S4, adding the second reaction solution dropwise into an alcohol solvent to generate precipitation, thereby obtaining the polyimide polymer; The aromatic dianhydride monomer is selected from one of 4,4'-(hexafluoroisopropylene) diphthalic anhydride, 4,4'-(4,4'-isopropyldiphenoxy) diphthalic anhydride or 4,4'-oxydiphthalic anhydride; Wherein, the structural formulas of the diamine monomer 1, diamine monomer 2 and the intermediate are as follows: In the structural formulas of the diamine monomer 1, diamine monomer 2, intermediate, and R3-O-R3, m, n, R 1 , R 2 , R 3 The definitions of m, n, R and 1 , R 2 , R 3 The definitions of correspond to the same.

5. The preparation method according to claim 4, characterized in that: In step S1, the catalyst is selected from at least one of isoquinoline, acetic anhydride, triethylamine or pyridine.

6. The preparation method according to claim 4, characterized in that: In step S1, the molar ratio of the catalyst to the diamine monomer 1 is 0.01 to 0.1:1; Preferably, in step S1, the molar ratio of the diamine monomer 1, the diamine monomer 2 and the aromatic dianhydride monomer is (0.45-0.55): (0.45-0.55): 1; Preferably, in step S3, the molar ratio of the intermediate, R3-O-R3 and triethylamine is 1:(1-5):(1-5).

7. The preparation method according to claim 4, characterized in that: In step S1, the polarity of the first strong polar solvent and the second strong polar solvent are respectively above 4.0; Preferably, the first strong polar solvent and the second strong polar solvent are independently selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide and m-methylphenol.

8. A polyimide film, characterized in that: The polyimide film comprises the polyimide polymer according to any one of claims 1 to 3.

9. A method for preparing the polyimide film according to claim 8, characterized in that: The steps include: The polyimide polymer according to any one of claims 1 to 3 and a third organic solvent are mixed and stirred to obtain a solution A; the solution A is coated on a substrate, evacuated, and subjected to a temperature increase and heat preservation treatment; after the treatment is completed, the solution is cooled, the substrate is peeled off, and dried to obtain the solution.

10. Use of the polyimide polymer according to any one of claims 1 to 3 or the polyimide film according to claim 8 in integrated circuits, electronics, microelectronics and flexible display materials.

Images