An intrinsic black polyimide, its preparation method and application

Abstract

This invention provides an intrinsic black polyimide, its preparation method, and its applications. The invention involves copolymerizing a mixed reaction system containing a thiophene-containing diamine monomer, a copolydiamine monomer, and a dianhydride monomer to obtain polyamic acid; then imidizing the polyimic acid to obtain an intrinsic black polyimide containing a thiophene structure in its main chain. This intrinsic black polyimide exhibits high blackness and low light transmittance, and the polyimide film prepared from it combines high blackness, low light transmittance, and excellent thermal stability and mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer materials technology, specifically relating to an intrinsic black polyimide, its preparation method, and its application. Background Technology

[0002] Polyimide (PI) is widely used in optical devices and aerospace due to its high thermal stability, good mechanical properties, and chemical resistance. With the rapid development of science and technology, the requirements for the comprehensive performance of PI materials in various fields are becoming increasingly stringent. Black PI, in particular, possesses excellent light-shielding properties, low light reflectance, and good environmental stability, making it suitable for applications in optics, electronics, and other fields with high shielding requirements. Conventional PI exhibits a yellow color and high transparency due to its electronic conjugation effect and the formation of intramolecular and intermolecular charge-transfer complexes (CTCs) between electron-donating diamine residues and electron-withdrawing dianhydride residues. Current technologies typically prepare black PI by adding black fillers such as carbon black and graphite. However, the aggregation of these filler particles easily leads to deterioration of mechanical properties, and achieving better dispersion of filler particles usually requires time-consuming, expensive, and complex modification and dispersion processes.

[0003] For example, prior art CN102529262A discloses a method for preparing a high-temperature resistant coating black polyimide film by coating with acrylic black matte ink. In this method, the black coating applied by the ink is prone to fading and unevenness, and the cost is also higher. Another prior art CN102260408A discloses a method for adding black filler to polyamic acid (PAA) and then imidizing it to form a film. In this method, the black filler is also prone to agglomeration and uneven dispersion, leading to a deterioration in the mechanical properties of the film. Prior art CN113563212B discloses a method for preparing an intrinsically black polyimide film by introducing anthraquinone derivative tetraamine monomer. It achieves intrinsic blackness by utilizing the conjugated structure of the anthraquinone chromophore. However, the rigid fused ring structure of the anthraquinone chromophore reduces the flexibility of the molecular chain, and the steric hindrance effect of the monomer structure disrupts the regular stacking between molecular chains, resulting in insufficient toughness, low elongation at break, and mechanical properties that need improvement.

[0004] It is evident that developing an intrinsically black polyimide film with high blackness, low light transmittance, and excellent mechanical properties is one of the urgent problems to be solved. Summary of the Invention

[0005] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions:

[0006] A first aspect of the present invention provides an intrinsic black polyimide having a structure as shown in formula (I):

[0007] ;

[0008] Where 0 < n < 200, 0 < m < 200, and Ar1 and Ar2 are independently selected from any one of the structures shown in a-1 to a-7:

[0009] ;

[0010] In the structures shown in a-1 to a-7, the dotted line represents the access position of the dianhydride;

[0011] Ar3 is selected from any one of the structures shown in b-1 to b-6:

[0012] ;

[0013] In the structures shown in b-1 to b-6, the dotted line represents the access position of the diamine;

[0014] Ar4 is selected from any one of the structures shown in c-1 to c-5:

[0015]

[0016] In the structures shown in c-1 to c-5, the dotted line represents the access position of the diamine.

[0017] The main chain of the intrinsic black polyimide provided by the present invention contains a thiophene structure, which has high blackness, low light transmittance, and also has excellent thermal stability and mechanical properties. This intrinsic black polyimide solves the problem of mechanical property deterioration caused by filler agglomeration and uneven dispersion in filler-type black polyimides, and at the same time overcomes the defects of easy color fading, uneven coating, and high cost in coating-type black polyimides, as well as the shortcoming of insufficient toughness and low elongation at break in existing intrinsic black polyimides (such as intrinsic black polyimides prepared based on anthraquinone derivative tetraamine monomers).

[0018] In some embodiments, the intrinsic black polyimide includes one or more combinations of the following formulas I-1 to I-5:

[0019] .

[0020] In some embodiments, when Ar1 and Ar2 are the same, 10 mol% to 100 mol% of Ar3 is the residue of 4,4'-diaminodiphenyl ether (ODA).

[0021] The second aspect of the present invention provides a method for preparing the intrinsic black polyimide according to any one of the above technical solutions, including: subjecting a mixed reaction system containing a thiophene-structured diamine monomer, a copolymer diamine monomer, and a dianhydride monomer to copolymerization reaction to obtain a polyamic acid;

[0022] The polyimide acid is imidized to obtain intrinsic black polyimide.

[0023] In some embodiments, the thiophene-containing diamine monomer includes one or more of the following: 4,4'-([2,2'-bithiophene]-5,5'-diyl)bis(3-methylaniline) (structure shown in C-1 below), 4,4'-(thiophene-2,5-diyl)diphenylamine (structure shown in C-2 below), 4,4'-(thiopheno[3,2-b]thiophene-2,5-diyl)bis(3-methylaniline) (structure shown in C-3 below), dibenzo[b,d]thiophene-3,7-diamine (structure shown in C-4 below), and [2,2':5',2''-trithiophene]-3',4'-diamine (structure shown in C-5 below).

[0024] .

[0025] In some embodiments, the copolydiamine monomer includes one or more of the following: 4-aminophenyl-4-aminobenzoate (structure shown in B-1 below), 2,-trifluoromethyl-1,4-phenylenediamine (structure shown in B-2 below), 2,5-bis(trifluoromethyl)-1,4-phenylenediamine (structure shown in B-3 below), 2,5-dimethyl-1,4-phenylenediamine (structure shown in B-4 below), N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-diphenyl]-4,4'-diyl)bis(4-aminobenzamide) (structure shown in B-5 below), and 4,4'-diaminodiphenyl ether (structure shown in B-6 below).

[0026] .

[0027] In some embodiments, the dianhydride monomer includes 5,5'-(1,4-phenylene)bis(hexahydro-4,7-methyleneisobenzofuran-1,3-dianhydride) (structure shown in A-1 below), pyromellitic dianhydride (structure shown in A-2 below), and octahydro-3H,3''H-bisspiro[[4,7]methyleneisobenzofuran-5,1'-cyclopentane-3',5''-[4,7]methyleneisobenzofuran]-1,1'',3,3''-dianhydride (structure shown in A-3 below). The structure is shown below. It can be one or a combination of multiple of the following: cyclobutano[1,2-c:3,4-c']difuran-1,3,4,6-tetracarboxylic dianhydride (structure shown in A-4 below), 5,5'-oxobis(isobenzofuran-1,3-dianhydride) (structure shown in A-5 below), [4,5'-biisobenzofuran]-1,1',3,3'-tetracarboxylic dianhydride (structure shown in A-6 below), and 3,3',4,4'-biphenyltetracarboxylic dianhydride (structure shown in A-7 below).

[0028] .

[0029] In some embodiments, the molar ratio of the thiophene-containing diamine monomer to the copolydiamine monomer in the mixed reaction system is 10:90 to 90:10, preferably 10:90 to 20:80. Within this range, the inherent excellent properties of the substrate PI film can be preserved.

[0030] In some embodiments, the molar ratio of the thiophene-containing diamine monomer to the dianhydride monomer in the mixed reaction system is 10:100 to 20:100.

[0031] In some embodiments, the copolymerization reaction is carried out at a temperature of 0-30°C, for example, at room temperature.

[0032] In some embodiments, the copolymerization reaction takes 24 to 48 hours.

[0033] In some embodiments, the method of imidizing the polyimide acid includes heat treatment.

[0034] In some embodiments, the heat treatment temperature is 150°C to 350°C.

[0035] In some embodiments, the heat treatment time is 5h to 8h.

[0036] In some embodiments, the copolymerization reaction is carried out under a protective atmosphere. The protective atmosphere can be any protective atmosphere known in the art, such as any one or more combinations of argon and nitrogen.

[0037] In some embodiments, the mixed reaction system further includes a polar organic solvent. The polar organic solvent can be any suitable organic solvent known in the art, such as one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, but is not limited thereto. The amount of solvent used can, for example, make the solid content of the mixed reaction system 5 wt% to 30 wt%.

[0038] A second aspect of the present invention provides an intrinsic black polyimide, which is prepared by the preparation method described in any of the technical solutions.

[0039] A third aspect of the present invention provides a polyimide article comprising the intrinsic black polyimide described in any of the technical solutions. The polyimide article may be, for example, a film, a colloid, a resin block, etc., but is not limited thereto.

[0040] A fourth aspect of the present invention provides a black polyimide film comprising the intrinsic black polyimide described in any of the technical solutions.

[0041] In some embodiments, the thickness of the black polyimide film is 8 μm to 100 μm.

[0042] In some embodiments, the black polyimide film has a light transmittance of less than 80% in the 400nm~800nm ​​range.

[0043] In some embodiments, the glass transition temperature of the black polyimide film is above 350°C.

[0044] In some embodiments, a 5% mass loss of the black polyimide film corresponds to a temperature above 500 °C.

[0045] A fourth aspect of the present invention provides a method for preparing a black polyimide film, comprising:

[0046] Based on the preparation method described in any of the above technical solutions, the polyamic acid is first prepared;

[0047] A solution containing the polyamic acid is laid into a film and then heat-treated to obtain a black polyimide film.

[0048] In some embodiments, the concentration of polyamic acid in the solution is 5 wt% to 10 wt%. For example, after the copolymerization reaction is completed, it can be diluted to the concentration using the aforementioned polar organic solvent to give it good flowability.

[0049] In some embodiments, the heat treatment temperature is 150°C to 350°C.

[0050] In some embodiments, the heat treatment holding time is 5h to 8h.

[0051] In some embodiments, the heat treatment specifically includes: using programmed temperature rise for multi-stage heat preservation. For example, programmed temperature rise can be used to gradually increase the temperature to a first temperature, a second temperature, a third temperature, a fourth temperature, and a fifth temperature in the range of 150°C to 350°C, and to hold at each temperature for 1 hour to 2 hours.

[0052] The polyimide film prepared by the above method exhibits high blackness and low light transmittance in the 400-800 nm range; it also possesses good mechanical properties and a high glass transition temperature (e.g., T). g It can reach temperatures above 350 ℃ and has good heat resistance (e.g., T). d5% It can reach temperatures above 500℃.

[0053] Compared with the prior art, the present invention has at least some or all of the following beneficial effects: the intrinsic black polyimide provided by the present invention contains a thiophene structure in its main chain, which has high blackness and low light transmittance; the polyimide film based on this intrinsic black polyimide has high blackness, low light transmittance, excellent thermal stability and mechanical properties. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 These are images of the polyimide films obtained in Examples 1-10 of this invention;

[0056] Figure 2 These are the infrared spectra of the polyimide films prepared in Examples 1-10 of this invention;

[0057] Figure 3 This is a UV-Vis spectrum curve of the polyimide film prepared in Examples 1-10 of the present invention. Detailed Implementation

[0058] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0059] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0060] Example 1

[0061] This embodiment provides an intrinsic black polyimide with a thiophene structure in its main chain and an intrinsic black polyimide film prepared therefrom. The preparation method specifically includes:

[0062] Under nitrogen atmosphere, 4,4'-(thiophene-2,5-diyl)diphenylamine (TPBDA, 0.0533 g), 4,4'-diaminodiphenyl ether (ODA, 0.3604 g; molar ratio of TPBDA to ODA was 0.1:0.9), and N,N-dimethylformamide (DMAc, 1 mL) were first added to a 25 mL three-necked flask. Nitrogen gas was introduced and the mixture was mechanically stirred for 30 min. After most of the solid dissolved, pyromellitic dianhydride (PMDA, 0.4362 g) and 1.55 mL of DMAc were added to the three-necked flask to obtain a mixed reaction system. The solid content of the mixed reaction system was maintained at 25 wt.%.

[0063] Under mechanical stirring, the above-mentioned mixed reaction system was reacted at room temperature for 24 hours to obtain a polyamic acid-containing solution with a high viscosity. To facilitate subsequent pouring, the polyamic acid-containing solution was diluted to a concentration of 5 wt% using DMAc solvent.

[0064] A 5 wt% polyamic acid solution was filtered and cast onto a 5 × 10 cm dry, clean glass plate. The plate was then dried at 50°C, 60°C, and 70°C for 30 min each, followed by drying at 80°C for 180 min to remove the solvent. Subsequently, the plate was heated sequentially at 150°C, 200°C, 250°C, 300°C, and 350°C for one hour each to perform thermal imidization treatment, yielding an intrinsic black polyimide film, designated BPI-1. The glass plate was then immersed in deionized water to remove the film, which was then dried to remove surface moisture.

[0065] The intrinsic black polyimide film prepared in this embodiment contains polyimide with the following structure:

[0066] ;

[0067] Where m is 90 and n is 10.

[0068] Example 2

[0069] Example 2 is essentially the same as Example 1, except that the molar ratio of TPBDA to ODA in the mixed reaction system of Example 2 is 0.2:0.8, the mass of TPBDA is 0.1065 g, and the mass of ODA is 0.3204 g. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 2 is designated BPI-2.

[0070] Example 3

[0071] Example 3 is essentially the same as Example 1, except that the thiophene-containing diamine monomer used in Example 3 is 4,4'-([2,2'-bithiophene]-5,5'-diyl)bis(3-methylaniline) (DTPBDA), wherein the molar ratio of DTPBDA to ODA is 0.01:0.9, the mass of DTPBDA is 0.0753 g, and the mass of ODA is 0.3604 g. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 3 is designated BPI-3.

[0072] The intrinsic black polyimide film prepared in this embodiment contains polyimide with the following structure:

[0073]

[0074] Where m is 90 and n is 10.

[0075] Example 4

[0076] Example 4 is essentially the same as Example 3, except that the molar ratio of DTPBDA to ODA in the mixed reaction system of Example 4 is 0.2:0.8, the mass of DTPBDA is 0.1506 g, and the mass of ODA is 0.3204 g. The rest of the process is the same as in Example 3 and will not be repeated here. The polyimide film obtained in Example 4 is designated BPI-4.

[0077] Example 5

[0078] Example 5 is essentially the same as Example 1, except that the thiophene-containing diamine monomer used in Example 5 is 4,4'-(thieno[3,2-b]thiophene-2,5-diyl)bis(3-methylaniline) (TTBDA), wherein the molar ratio of TTBDA to ODA is 0.1:0.9, the mass of TTBDA is 0.0701 g, and the mass of ODA is 0.3204 g. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 5 is designated BPI-5.

[0079] The intrinsic black polyimide film prepared in this embodiment contains polyimide with the following structure:

[0080] ;

[0081] Where m is 90 and n is 10.

[0082] Example 6

[0083] Example 6 is essentially the same as Example 1, except that the thiophene-containing diamine monomer used in Example 6 is dibenzo[b,d]thiophene-3,7-diamine (DBTDA), wherein the molar ratio of DBTDA to ODA is 0.1:0.9, the mass of DBTDA is 0.214 g, and the mass of ODA is 1.80 g. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 6 is designated BPI-6.

[0084] The intrinsic black polyimide film prepared in this embodiment contains polyimide with the following structure:

[0085]

[0086] Where m is 90 and n is 10.

[0087] Example 7

[0088] Example 7 is essentially the same as Example 6, except that in the mixed reaction system of Example 6, the molar ratio of DBTDA to ODA is 0.2:0.8, with DBTDA weighing 0.428 g and ODA weighing 1.6 g. The rest of the process is the same as in Example 6 and will not be repeated here. The polyimide film obtained in Example 7 is designated BPI-7.

[0089] Example 8

[0090] Example 8 is essentially the same as Example 1, except that the thiophene-containing diamine monomer used in Example 8 is [2,2':5',2''-terthiophene]-3',4'-diamine (BTPDA), wherein the molar ratio of BTPDA to ODA is 0.1:0.9, the mass of BTPDA is 0.278 g, and the mass of ODA is 1.80 g. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 8 is designated BPI-8.

[0091] The intrinsic black polyimide film prepared in this embodiment contains polyimide with the following structure:

[0092]

[0093] Where m is 90 and n is 10.

[0094] Example 9

[0095] The difference between Example 9 and Example 8 is that in Example 9, the molar ratio of BTPDA to ODA in the mixed reaction system is 0.2:0.8, with BTPDA weighing 0.557 g and ODA weighing 1.60 g. The rest of the process is the same as in Example 8 and will not be repeated here. The polyimide film obtained in Example 9 is designated BPI-9.

[0096] Example 10

[0097] The only difference between Example 10 and Example 1 is that the molar ratio of TPBDA to ODA in the mixed reaction system of Example 10 is 0.9:0.1. The rest of the process is the same as in Example 1 and will not be repeated here. The polyimide film obtained in Example 10 is designated BPI-10.

[0098] Examples 11-16

[0099] Examples 11-16 are basically the same as Example 1, except that the types of copolydiamine monomers and dianhydride monomers used are varied according to Table 1. The rest are the same as in Example 1.

[0100] Table 1

[0101]

[0102] Comparative Example 1

[0103] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not use TPBDA, but only PMDA and ODA are reacted, and the amount of PMDA in Comparative Example 1 is the same as the total amount of TPBDA and PMDA in Example 1. The rest of the procedures are the same as in Example 1, and will not be repeated here.

[0104] The mechanical and optical properties of the intrinsic black polyimide films prepared in the above-mentioned embodiments and comparative examples were tested using films with a thickness of 30 μm. The test results are shown in Table 2.

[0105] Table 2. Optical and mechanical properties of polyimide films in the examples and comparative examples.

[0106]

[0107] Figure 1 These are images of the polyimide films prepared in Examples 1-10. Figure 2 These are the infrared spectra of the polyimide films prepared in Examples 1-10.

[0108] As shown in Table 2, compared with Comparative Example 1, the intrinsic black polyimide film prepared in the embodiments of the present invention has comparable mechanical properties.

[0109] The intrinsic black polyimide films prepared in Examples 1-10 and the film of Comparative Example 1 were subjected to ultraviolet-visible transmission spectroscopy tests, and their ultraviolet transmission spectral data are shown in Table 2. Figure 3 These are the UV-Vis spectrum curves of the polyimide films prepared in Examples 1-10. Analysis shows that the transmittance at 600 nm (T0.05) of the film in Comparative Example 1 is... 600 The cutoff wavelength (λ) reaches 85%. cut-off The Tnm of the intrinsic black polyimide films of Examples 1-9 is only 410 nm; while the Tnm of the intrinsic black polyimide films of Examples 1-9 is only 410 nm. 600 Significantly reduced (e.g., the T of the film in Example 10) 600 The optical absorption performance of the thin film provided by the present invention is significantly improved compared with that of Comparative Example 1, with a reduction of only 0.8% and a significant red shift in the cutoff wavelength (as shown in Example 10, the film can reach up to 602 nm).

[0110] To characterize the optical black state performance of the thin films, the L values ​​of the thin films prepared in Examples 1-10 were obtained by colorimetry. Detailed optical and mechanical property data are shown in Table 2. In Table 2, It represents the shade of black and white, ranging from 0 to 100, with no negative values. The larger the value, the whiter (brighter) the color. The smaller the value, the darker the film; as shown in Table 2, compared to the film in Comparative Example 1 ( =85), the thin films of Examples 1-10 of the present invention All showed varying degrees of decrease, further illustrating the optimization of its optical absorption characteristics.

[0111] The intrinsic black polyimide and polyimide films prepared in Examples 11-13 have properties comparable to those in Examples 2 and 4; the intrinsic black polyimide and polyimide films prepared in Examples 14-16 have optical properties comparable to those in Example 5, but slightly weaker mechanical properties compared to Example 5.

[0112] In summary, the black polyimide film prepared by the intrinsic black polyimide provided by this invention has excellent optical and mechanical properties, and can solve the problems of reduced film elongation due to uneven filler content in dye-doped black polyimide.

[0113] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0114] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0115] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A black polyimide film, characterized by, The black polyimide film comprises an intrinsic black polyimide having a structure shown in formula (I): ； where 0 < n < 200, 0 < m < 200, and Ar1 and Ar2 are independently selected from any one of the structures shown in a-1 to a-7: ； In the structures shown in a-1 to a-7, the dotted line represents the access position of the dianhydride; Ar3 is selected from any one of the structures shown in b-1 to b-6: ； In the structures shown in b-1 to b-6, the dotted line represents the access position of the diamine; Ar4 is selected from any one of the structures shown in c-1, c-3, and c-5: ； In the structures shown in c-1, c-3, and c-5, the dotted line represents the access position of the diamine; Moreover, the light transmittance of the black polyimide film at 400 nm to 800 nm is 80% or less.

2. The black polyimide film according to claim 1, characterized in that: The thickness of the black polyimide film is 8 μm to 100 μm.

3. The black polyimide film according to claim 1, characterized in that: The glass transition temperature of the black polyimide film is 350 °C or higher.

4. The black polyimide film according to claim 1, characterized in that: The temperature at which the black polyimide film loses 5% of its mass is 500 °C or higher.

5. The method for preparing the black polyimide film according to any one of claims 1-4, characterized in that, Comprising: Subjecting a mixed reaction system containing a thiophene-structured diamine monomer, a copolymerized diamine monomer, and a dianhydride monomer to copolymerization reaction to obtain a polyamic acid; Coating a solution containing the polyamic acid and performing heat treatment to obtain a black polyimide film; where the thiophene-structured diamine monomer includes one or a combination of more of 4,4'-([2,2'-bithiophene]-5,5'-diyl)bis(3-methylaniline), 4,4'-(thieno[3,2-b]thiophene-2,5-diyl)bis(3-methylaniline), [2,2':5',2''-terthiophene]-3',4'-diamine; The copolymerized diamine monomer includes one or a combination of more of 4-aminophenyl 4-aminobenzoate, 2-trifluoromethyl-1,4-phenylenediamine, 2,5-bis(trifluoromethyl)-1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide), 4,4'-diaminodiphenyl ether; The dianhydride monomer includes one or a combination of more of 5,5'-(1,4-phenylene)bis(hexahydro-4,7-methanoisobenzofuran-1,3-dianhydride), pyromellitic dianhydride, octahydro-3H,3''H-bisspiro[[4,7]methanoisobenzofuran-5,1'-cyclopentane-3',5''-[4,7]methanoisobenzofuran]-1,1'',3,3''-dianhydride, cyclobutano[1,2-c:3,4-c']difuran-1,3,4,6-tetracarboxylic dianhydride, 5,5'-oxybis(isobenzofuran-1,3-dianhydride), [4,5'-biphenyldiisobenzofuran]-1,1',3,3'-tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride; 6. The method for preparing the black polyimide film according to claim 5, characterized in that: The molar ratio of the thiophene-structured diamine monomer to the copolymerized diamine monomer in the mixed reaction system is 10:90 to 90:

10.

7. The method for preparing the black polyimide film according to claim 5, characterized in that: The molar ratio of the thiophene-containing diamine monomer to the dianhydride monomer in the mixed reaction system is 10:100 to 20:

100.

8. The method for preparing the black polyimide film according to claim 5, characterized in that: The copolymerization reaction is carried out at a temperature of 0~30℃; and / or the copolymerization reaction is carried out for a time of 24h~48h.

9. The method for preparing the black polyimide film according to claim 5, characterized in that: The method for imidizing the polyamic acid includes heat treatment at a temperature of 150°C to 350°C for a duration of 5 to 8 hours.

10. The method for preparing the black polyimide film according to claim 5, characterized in that: The copolymerization reaction was carried out under a protective atmosphere.

11. The method for preparing the black polyimide film according to claim 5, characterized in that: The mixed reaction system also includes a catalyst.

12. The method for preparing the black polyimide film according to claim 5, characterized in that: The mixed reaction system also includes a polar organic solvent.

13. The method for preparing the black polyimide film according to claim 5, characterized in that: The concentration of polyamic acid in the solution is 5wt%~10wt%.

14. The method for preparing the black polyimide film according to claim 5, characterized in that: The heat treatment temperature is 150℃~350℃.

15. The method for preparing the black polyimide film according to claim 5, characterized in that: The heat treatment holding time is 5h~8h.

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