CN114213657A

CN114213657A - Intrinsic black polyimide and preparation method and application thereof

Info

Publication number: CN114213657A
Application number: CN202210051641.4A
Authority: CN
Inventors: 刘亦武; 谢丰云; 谭井华; 沈俊逸; 黄杰; 陈成亮; 周栋
Original assignee: Hunan University of Technology
Current assignee: Hunan University of Technology
Priority date: 2022-01-17
Filing date: 2022-01-17
Publication date: 2022-03-22

Abstract

The invention discloses intrinsic black polyimide and a preparation method and application thereof. The intrinsic black polyimide adopts a diamine monomer containing a tetraphenylcyclopentadienone structure with large conjugation characteristic and a tetracarboxylic dianhydride monomer as raw materials, polyamide acid is obtained through polymerization, and polyimide is obtained through imidization. The diamine monomer containing the tetraphenylcyclopentadienone structure with the large conjugation characteristic has wide strong absorption in a visible light region, and the diamine monomer is introduced into a polyimide molecular chain, so that the polyimide has excellent visible light absorption capacity, and further has an intrinsic black characteristic, and meanwhile, the polyimide also has excellent solubility, heat resistance, electrical insulation performance and mechanical performance. The synthesis process is simple and suitable for industrial production. The intrinsic black polyimide prepared by the invention has excellent visible light shielding performance, mechanical property and electrical insulating property, and can be widely applied to the fields of microelectronics, photoelectricity, war industry, aerospace and the like.

Description

Intrinsic black polyimide and preparation method and application thereof

Technical Field

The invention relates to the field of material science, in particular to intrinsic black polyimide and a preparation method thereof.

Background

The black Polyimide (PI) film has good light-shielding property, insulating property, high-temperature stability and other properties, and is widely applied to the fields of optics, electronics, aerospace and the like. If the stray light interference eliminating device is used for a satellite antenna, the interference of various stray light on an imaging system and a sensor can be eliminated or avoided, and the normal working performance of the antenna is kept; the light absorption film can be used for light fixed attenuators and light terminal instruments; the coating electronic element can form images by a photocopying method; the circuit board covering film can be used for covering circuits to prevent reverse engineering and can avoid the degradation effect of long-time light radiation on the circuits; for optical applications such as headlights and camera flashes, light reflection can be avoided, and the contrast of the light source can be enhanced. In recent years, the market demand for black polyimide cover films has been increasing due to the increasing abundance of end uses.

Currently, the black polyimide film is mainly prepared by adding various light-shielding substances such as carbon black, graphite, metal oxide, aniline black, perylene black and other inorganic or organic black pigments to polyamic acid (PAA), and performing casting drying, chemical or high-temperature thermal imidization treatment to form a film, such as patents US 851107B 2, CN102260408A, CN201210310734.0, CN201611246264.0, and the like. Due to the low cost, high color yield and high heat resistance of carbon black, most black polyimides have carbon black as the main black filler. However, carbon black is a conductive material, has large surface energy, is easy to agglomerate, and is easy to cause uneven color of a film and deterioration of mechanical property and electrical insulation property; the metal oxide can also cause the reduction of the insulating property and the mechanical property of the polyimide film, and the coloring property of the polyimide film is not as good as that of carbon black; the organic black dye has a problem of poor heat resistance, and is easily precipitated along with solvent volatilization in a high-temperature imide process. The development of intrinsic black polyimide having excellent mechanical properties and electrical insulation properties is an effective way to solve this problem.

At present, there are two main ways for designing and synthesizing intrinsic black polyimide:

(1) increase the formation of Charge Transfer Complexes (CTCs) of the PI molecular chains. Because PI has stronger CTC effect and generally presents yellow or brown darker appearance, Liu et al [ Journal of Polymer Research,2019,26(7):1-10] adopt rich electron diamine 4,4 '-diaminodiphenylamine (NDA), 4' -diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) to polymerize to prepare PI, because the introduction of the rich electron diamine NDA improves the capability of forming charge transfer complex between diamine monomer and dianhydride monomer, the prepared PI presents darker color, even if the NDA is increased to 100 percent, namely the PI is prepared by NDA and PMDA, the prepared PI still does not reach ideal black, and the complete black of polyimide can not be well realized by enhancing the CTC effect. In addition, the invention patent publication No. CN109180936A prepared a series of intrinsic PI by the same method, and could not achieve complete black.

(2) Introducing chromophores and auxochromes into the molecular chain. Patent CN111574426A discloses a series of intrinsic black polyimides prepared by synthesizing diamine monomer containing isoindigo structure and polymerizing it with commercial dianhydride monomer to obtain polyimide. An anthraquinone derivative monomer with a very high molar extinction coefficient is designed and synthesized by the invention patent with the publication number of CN113563212A, a plurality of auxochromic groups are introduced, and the auxochromic groups and ODA are copolymerized with PMDA in different proportions to prepare PI, but the mechanical property of a PI film is sharply reduced along with the increase of the content of the anthraquinone structure with a rigid plane structure.

More importantly, the intrinsic black PI reported above cannot be dissolved in organic solvents, and the processing and forming of insoluble and infusible polymers are very difficult, thus limiting the application fields. While the development trend of black PI films is demanding ultra-thinness, for example, in wireless charging device applications, black polyimide is expected to have excellent solubility, facilitating its processing into ultra-thin PI films. Therefore, the development of the intrinsic black PI material with excellent solubility can improve the molding processability of PI, further realize the preparation of the ultrathin black PI film, and has important significance for expanding the application field of black PI.

Therefore, the invention discloses a series of intrinsic black polyimides containing tetraphenylcyclopentadienone structures, which are prepared by polymerizing diamines and tetracarboxylic dianhydrides containing tetraphenylcyclopentadienone structures and having large conjugation characteristics. The polyimide has excellent visible light absorption capacity and further presents intrinsic black; meanwhile, the polyimide has excellent solubility, heat resistance, mechanical property and electrical insulation property, and has wide application prospect in the fields of microelectronics, photoelectricity, military industry, aerospace and the like. At present, no polyimide containing tetraphenylcyclopentadienone structure is reported.

Disclosure of Invention

The first purpose of the invention is to synthesize novel intrinsic black polyimide containing tetraphenylcyclopentadienone structure.

The second object of the present invention is to provide a method for preparing the intrinsic black polyimide containing tetraphenylcyclopentadienone structure.

The purpose of the invention is realized as follows:

an intrinsic black polyimide, the structural formula of the polyimide is shown as follows:

wherein: m is 5-10000, n is 0-10000;

wherein X is selected from one or more than one of the following structural formulas:

wherein R is₁Is any one of the following structural formulas:

R₂is any one of the following structural formulas:

wherein R is methyl, ethyl, propyl or butyl.

Wherein Y is selected from one or more than one of the following structural formulas:

wherein Z is selected from one or more than one of the following structural formulas:

the synthesis method of the polyimide containing the tetraphenylcyclopentadienone structure comprises the following reaction processes: in one or more inert gas atmospheres of nitrogen, helium and argon, dissolving a diamine monomer containing a tetraphenylcyclopentadienone structure and a commercial diamine monomer (optionally without adding the commercial diamine monomer) in one or more mixed polar aprotic solvents of N-methylpyrrolidone, dimethyl sulfoxide, dimethyl sulfone, sulfolane, 1, 4-dioxane, N-dimethylacetamide, N-dimethylformamide, m-cresol and tetrahydrofuran. Adding a dianhydride monomer after the diamine monomer is completely dissolved, wherein the mass ratio of the diamine monomer to the dianhydride monomer is 1: 0.9-1: 1.1, stirring and reacting for 2-48 h at-15-45 ℃ to obtain homogeneous and viscous polyamic acid precursor glue solution, then carrying out thermal imidization or chemical imidization on the polyamic acid precursor, and dehydrating to obtain the polyimide. The total mass of the diamine monomer containing the X and Y structures and the dianhydride monomer containing the Z structure accounts for 2-50% of the mass of the polyamic acid glue solution.

Further, the specific operation of the thermal imidization is: firstly, uniformly coating polyimide glue solution on a glass plate by scraping, then placing the glass plate in a vacuum oven for heating, wherein the temperature rise procedure is as follows: raising the temperature of the room temperature to 100 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 100 ℃ to 200 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 200 ℃ to 300 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 300 ℃ to 350-500 ℃, keeping the temperature for 0.1-1 h, cooling, taking out the polyimide film, and peeling the polyimide film from the glass.

Further, the specific operation of the chemical imidization is as follows: adding a dehydrating agent (acetic anhydride) and a catalyst (pyridine, triethylamine, sodium acetate or isoquinoline) into the polyamic acid glue solution, stirring for 0.5-2 h at 0-100 ℃, then blade-coating the glue solution on a glass plate, placing the glass plate into an oven, heating to 80-200 ℃, keeping the temperature for 0.2-2 h to remove the solvent, then carrying out vacuum high temperature to 320-450 ℃, keeping the temperature for 5-30 min to fully imidize, cooling, and then stripping the polyimide film from the glass plate.

Compared with the prior art, the beneficial effects are:

the invention prepares a novel polyimide material by introducing a tetraphenylcyclopentadienone-containing structure with large conjugation characteristic into a polyimide molecular chain. The electronic transition characteristic of the polyimide is regulated and controlled by introducing different electron withdrawing and donating groups and conjugated system groups with different sizes into the side group of the tetraphenylcyclopentadienone, so that the visible light absorption capacity of the polyimide is improved; meanwhile, the large volume containing the tetraphenylcyclopentadienone structure can effectively destroy the stacking of molecular chains, so that the free volume of the polyimide film is increased, the solubility of the polyimide is improved, and the dielectric constant of the polyimide film is reduced; in addition, the rigid aromatic structure can maintain the excellent mechanical and thermal properties of the polyimide. The intrinsic black polyimide containing the tetraphenylcyclopentadienone structure has excellent solubility, heat resistance, mechanical property and electrical insulation property, and can be used in the high and new technical fields of microelectronics, photoelectricity, military industry, aerospace and the like.

The preparation method of the intrinsic black polyimide containing the tetraphenylcyclopentadienone structure is simple, the preparation process is simple and various, and the method is suitable for industrial production. The polyimide has an intrinsic black characteristic through molecular structure design, does not need to be added with black shading substances or coated with black coatings on the surface to realize the light shading effect, has excellent solubility, mechanical property and electrical insulating property, and has important significance for expanding the application field of black PI materials.

Drawings

FIG. 1 is an infrared spectrum of an intrinsic black polyimide synthesized in examples 1 to 27. The infrared spectrum can confirm that the corresponding polyimide is successfully synthesized. 2955 and 2965cm^-1Stretching vibration peak near methyl, 1786 and 1720cm^-1The vicinity is an asymmetric and symmetric stretching vibration peak of carbonyl on an imine ring, 1517cm^-1Is a characteristic absorption peak of nitro, 1363cm^-1Around the peak of stretching vibration of imide ring, 1273cm^-1The vicinity is the stretching vibration peak of C-O, 1109cm^-1The vicinity is a C-F stretching vibration peak, 1100-700 cm^-1The vicinity is an Ar-H deformation vibration absorption peak.

FIG. 2 is a graph showing UV-visible light transmittance spectra of the intrinsic type black polyimides synthesized in examples 4, 6, 7, 8, 15, 18, 19, 20, 21, 23, and 24, which have excellent visible light absorption properties in comparison with the conventional polyimide Kapton.

FIG. 3 is a photograph showing the polyimide prepared in examples 1 to 27, which is an intrinsic black polyimide, wherein the tetraphenylcyclopentadienone-containing polyimide is opaque and black, has good flexibility, and has good mechanical properties.

Detailed Description

The invention is further illustrated by the following examples. The method of the present invention is not limited to the following description, and any modifications and changes made within the spirit and scope of the present invention should be considered within the scope of the present invention.

Example 1:

2.8666g (3.5mmol) of 3,4-di ([1,1'-biphenyl ] -4-yl) -2,5-bis (4- (4-aminophthalenyl-1-yl) phenyl) cyclopenta-2,4-dienone and 18.4ml of dried N-methylpyrrolidone (NMP) were put into a 50ml round bottom flask under the protection of argon in a clean room, and after dissolving them by stirring, 1.5548g (3.5mmol) of 4,4' - (hexafluoroisopropylene) diphthalic anhydride (6FDA) was added to obtain a solid content of about 18%, and the mixture was reacted at 0 ℃ for 8 hours to obtain the corresponding PAA dope.

An imidization reagent is prepared by taking NMP, acetic anhydride and isoquinoline as volume ratio of 2:2:1, 6ml of imidization reagent is dripped into PAA glue solution, and chemical imidization is carried out for 1 hour under stirring at room temperature. The PI glue solution of chemical imidization is spread on a clean glass plate by scraping, and the thickness of the liquid film is controlled by adjusting the effective height of the scraper. Heating to 120 ℃ in a high-temperature blast drying oven, keeping the temperature constant for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature constant for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample, and removing the PI film from the glass plate.

The molecular structural formula of the intrinsic black PI in this example is as follows:

example 2:

1.9025g (2mmol) of 2,5-bis (4'-amino- [1,1' -biphenyl ] -3-yl) -3,4-bis (4- (9, 9-dimethyl-9H-fluoro-2-yl) phenyl) cyclopenta-2,4-dienone and 21.2ml of dried N, N-dimethylacetamide (DMAc) were added to a 50ml round bottom flask under nitrogen protection in a clean room, and after dissolving them with stirring, 6FDA 0.8885g (2mmol) was added to react at-10 ℃ for 48 hours to obtain the corresponding PAA colloidal solution.

An imidizing reagent is prepared by taking DMAc, acetic anhydride and pyridine as the volume ratio of 6:3:1, 5ml of imidizing reagent is dripped into PAA glue solution, and chemical imidization is carried out for 1.5h under the stirring at the temperature of 30 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 140 ℃ in an air-blast drying oven, keeping the temperature for 0.8h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 440 ℃, keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 3:

in a clean room, a 50ml round bottom flask under argon protection was charged with 2,5-bis (4 "-amino- [1,1':4', 1" -terphenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2, 4-diene 3.0195g (4mmol) and 20ml of dry N, N-Dimethylformamide (DMF), and after stirring to dissolve, 6FDA 1.7770g (4mmol) with a solid content of about 20% was added and reacted at 0 ℃ for 8h to obtain the corresponding PAA dope.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 6ml of the imidizing reagent into PAA glue solution, and stirring at 40 ℃ to perform chemical imidization for 2 hours. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 80 ℃ in an air-blowing drying oven, keeping the temperature for 0.6h, keeping the temperature for 1h after the temperature is 160 ℃, removing the solvent, transferring to a vacuum drying oven, quickly heating to 330 ℃, keeping the temperature for 30min to fully imidize the PI film, cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 4:

in a clean room, 2,5-bis (4' - (4-aminophenyl) - [1,1' -biphenyl ] -3-yl) -3,4-bis (3-methoxyphenyl) cyclopenta-2,4-dienone 3.2438g (4mmol) and 20.9ml of dried NMP were added to a 50ml round bottom flask under protection of argon and nitrogen, and after dissolving them by stirring, 1.2409g (4mmol) of 4,4' -oxydiphthalic anhydride (OPDA) having a solid content of about 19% was added, and the mixture was reacted at-15 ℃ for 12 hours to obtain a PAA dope solution.

An imidizing reagent is prepared by taking NMP, acetic anhydride and isoquinoline as the volume ratio of 6:3:1, 6ml of imidizing reagent is dripped into PAA glue solution, and chemical imidization is carried out for 0.5h under stirring at 60 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 180 ℃ in an air drying oven, keeping the temperature for 0.4h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 350 ℃, keeping the temperature for 20min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 5:

in a clean room, 2,5-di ([1,1' -biphenyl ] -4-yl) -3,4-bis (4- (6-aminopyridin-3-yl) phenyl) cyclopenta-2,4-dienone 2.8835g (4mmol) and 17.8ml of dried m-cresol were added under protection of helium gas in a 50ml round bottom flask, and after dissolving by stirring, PMDA 0.8725g (4mmol) with a solid content of about 17% was added, and reacted at-5 ℃ for 30 hours to obtain the corresponding PAA dope.

Preparing an imidization reagent by taking m-cresol, acetic anhydride and triethylamine as volume ratio of 6:3:1, dripping 6ml of imidization reagent into PAA glue solution, and stirring at 45 ℃ for chemical imidization for 1.5 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 90 ℃ in an air-blast drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 360 ℃, keeping the temperature for 15min to fully imidize the PI film, then cooling to room temperature, taking out the sample, and removing the PI film from the glass plate.

example 6:

in a clean room, 2,5-bis (4'- (4-aminophenyl) - [1,1' -biphenyl ] -3-yl) -3,4-bis (3-methoxyphenyl) cyclopenta-2,4-dienone 2.3790g (4mmol) and 21.2ml of dried DMAc were added to a 50ml round bottom flask under argon protection, and after dissolving by stirring, 1.1769g (4mmol) of 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) was added to react at 35 ℃ for 3 hours to obtain the corresponding PAA colloidal solution.

An imidizing reagent is prepared by taking DMAc, acetic anhydride and pyridine as the volume ratio of 6:3:1, 6ml of imidizing reagent is dripped into PAA glue solution, and chemical imidization is carried out for 1h under stirring at 35 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 110 ℃ in an air drying oven, keeping the temperature for 0.8h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 370 ℃, keeping the temperature for 25min to fully imidize the PI film, then cooling to room temperature, taking out the sample, and removing the PI film from the glass plate.

example 7:

in a clean room, 3,4-bis (3- (6-aminophthalalen-2-yl) phenyl) -2,5-bis (4-hydroxyphenyl) cyclopenta-2,4-dienone 2.7953g (4mmol) and 19.7ml of dry DMF were added under the protection of argon gas in a 50ml round bottom flask, and after dissolving them by stirring, 1.2889g (4mmol) of 3,3',4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) was added and the solid content was about 18%, and reacted at 45 ℃ for 2 hours to obtain the corresponding PAA glue solution. Scraping and coating the PAA glue solution on a clean glass plate, heating the glass plate to 100 ℃ in a vacuum drying oven at room temperature, keeping the temperature for 1h, heating the glass plate to 200 ℃ from 100 ℃ for 0.5h, heating the glass plate to 300 ℃ for 0.2h, heating the glass plate to 380 ℃ from 300 ℃ for 0.5h, cooling the glass plate to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 8:

in a clean room, 3,4-bis (4'-amino- [1,1' -biphenyl ] -3-yl) -2,5-bis (4'- (dimethyllamino) - [1,1' -biphenyl ] -3-yl) cyclopenta-2,4-dienone 3.2202g (4mmol) and 19.9ml of dry DMF were added under argon protection to a 50ml round bottom flask, and after dissolving by stirring, 6FDA 1.7770g (4mmol) with a solid content of about 21% was added and reacted at 25 ℃ for 5 hours to obtain the corresponding PAA dope. And (3) coating the PAA glue solution on a clean glass plate, heating the glass plate to 100 ℃ in a vacuum drying oven at room temperature, keeping the temperature for 0.7h, heating the glass plate to 200 ℃ from 100 ℃ and keeping the temperature for 1.5h, heating the glass plate to 300 ℃ and keeping the temperature for 1h, heating the glass plate to 350 ℃ from 300 ℃ and keeping the temperature for 1h, cooling the glass plate to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 9:

in a clean room, 2,5-bis (4- (2-aminopyrimidin-5-yl) phenyl) -3,4-bis (4- (naphthalene-2-yl) phenyl) cyclopenta-2,4-dienone 3.2919g (4mmol) and 48.3ml dry DMF were added under argon protection to a 100ml round bottom flask, stirred to dissolve them, 6FDA 1.7770g (4mmol) was added to obtain a solid content of about 10%, and reacted at 15 ℃ for 10h to obtain the corresponding PAA glue solution. And (3) coating the PAA glue solution on a clean glass plate by scraping, heating the glass plate to 100 ℃ in a vacuum drying oven at room temperature, keeping the temperature for 1.5h, heating the glass plate to 200 ℃ from 100 ℃ and keeping the temperature for 1h, heating the glass plate to 300 ℃ and keeping the temperature for 1.3h, heating the glass plate to 400 ℃ from 300 ℃ and keeping the temperature for 0.2h, then cooling the glass plate to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 10:

in a clean room, 2,5-di ([1,1':4',1 "-terphenyl ] -4-yl) -3,4-bis (4- (6- (4-aminophenyl) naphthalene-2-yl) phenyl) cyclopenta-2,4-dienone 2.2472g (2mmol) and 47.3ml of dried DMAc were added under argon protection, and after dissolving by stirring, 6FDA 0.8885g (2mmol) with a solid content of about 5% was added, and reacted at 10 ℃ for 8 hours to obtain the corresponding PAA dope solution. The PAA glue solution is spread on a clean glass plate by scraping, the temperature is raised to 100 ℃ in a vacuum drying oven and then is kept constant for 0.5h, the temperature is raised from 100 ℃ to 200 ℃ and then is kept constant for 0.8h, the temperature is raised from 200 ℃ to 300 ℃ and then is kept constant for 0.7h, the temperature is raised from 300 ℃ to 450 ℃ and then is kept constant for 0.1h, then the temperature is cooled to room temperature, a sample is taken out, and the PI film is removed from the glass plate.

example 11:

this example provides a method for synthesizing a black PI copolymer, which is prepared by copolymerizing two diamine monomers containing tetraphenylcyclopentadienone structures with 6 FDA.

1.8872g (2.5mmol) of 2,5-bis (4 "-amino- [1,1':4', 1" -tert-phenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2,4-dienone and 1.7471g (2.5mmol) of 3,4-bis (3- (6-aminonaphthalene-2-yl) phenyl) -2,5-bis (4-hydroxyphenyl) cyclopenta-2,4-dienone were added to a 50ml round bottom flask under argon protection in a clean room, 20.7ml of dry DMF was added, FDA was stirred to dissolve it, and then dianhydride monomer 6 2.2212g (5mmol) was added to obtain a solid content of about 23%, and reacted at 0 ℃ for 8h to obtain the corresponding PAA colloidal solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 6ml of the imidizing reagent into PAA glue solution, and stirring at 10 ℃ for chemical imidization for 2 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 100 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 380 ℃, keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 12:

this example provides a method for synthesizing black PI copolymer, which is prepared by copolymerizing two diamines of tetraphenylcyclopentadienone-containing diamine 2,5-bis (4 "-amino- [1,1':4', 1" -terphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and TFDB with 6FDA, wherein the amount of tetraphenylcyclopentadienone-containing diamine monomer material in this example accounts for 80% of the total diamine material.

3.0195g (4mmol) of 2,5-bis (4'-amino- [1,1':4', 1' -terphenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2,4-dienone and 0.3202g TFDB (1mmol) were added to a 50ml round bottom flask under argon protection in a clean room, 20ml of dry DMF was added and dissolved by stirring, then dianhydride monomer 6FDA 2.2212g (5mmol) was added and the solid content was about 23% and reacted at 0 ℃ for 8h to obtain the corresponding PAA glue solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and triethylamine (6: 3: 1) as volume ratios, dropwise adding 6ml of the imidizing reagent into the PAA glue solution, and stirring at 20 ℃ for chemical imidization for 1 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 100 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 380 ℃, keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 13:

this example provides a method for synthesizing a black polyimide copolymer, which employs two diamines, namely, diamine 2,5-bis (4 "-amino- [1,1':4', 1" -terphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and TFDB, containing tetraphenylcyclopentadienone structure to copolymerize with 6FDA, wherein the amount of the tetraphenylcyclopentadienone-containing diamine substance in this example accounts for 70% of the total diamine substance.

In a clean room, 2.6421g (3.5mmol) of 2,5-bis (4'-amino- [1,1':4', 1' -terphenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2,4-dien-1-one and 0.4803g TFDB (1.5mmol) were added to a 50ml round bottom flask under argon protection, 13.2ml of dry DMF was added and dissolved by stirring, then dianhydride monomer 6FDA 2.2212g (5mmol) was added, the solid content was about 30%, and the reaction was carried out at 0 ℃ for 8h to obtain the corresponding PAA liquid cement.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 6ml of the imidizing reagent into PAA glue solution, and stirring at 20 ℃ for chemical imidization for 1 hour. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 100 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 380 ℃, keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 14:

this example provides a method for synthesizing black PI copolymer, which is prepared by copolymerizing 6FDA with diamine 2,5-bis (4'-amino- [1,1':4', 1' -terphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and TFDB containing tetraphenylcyclopentadienone structure, wherein the amount of tetraphenylcyclopentadienone containing diamine substance in this example accounts for 60% of the total diamine substance.

2.2646g (3mmol) of 2,5-bis (4'-amino- [1,1':4', 1' -terphenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2,4-dien-1-one and 0.6405g of TFDB (2mmol) were added to a 50ml round bottom flask under argon protection in a clean room, 10.8ml of dry DMAc was added, and after stirring to dissolve it, 6FDA 2.2212g (5mmol) of dianhydride monomer was added, the solid content was about 35%, and the reaction was carried out at 0 ℃ for 8h to obtain the corresponding PAA glue solution.

An imidizing reagent is prepared by taking DMAc, acetic anhydride and isoquinoline as volume ratio of 6:3:1, 6ml of imidizing reagent is dripped into PAA glue solution, and chemical imidization is carried out for 1h under stirring at 20 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 100 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 380 ℃, keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 15:

this example provides a method for synthesizing a black PI copolymer, in which two diamines, namely, diamine 2,5-bis (4 "-amino- [1,1':4', 1" -terphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and TFDB, containing tetraphenylcyclopentadienone structure are copolymerized with 6FDA, and the amount of tetraphenylcyclopentadienone-containing diamine substance in this example accounts for 50% of the total diamine substance.

1.8872g (2.5mmol) of 2,5-bis (4'-amino- [1,1':4', 1' -terphenyl ] -4-yl) -3,4-bis (3-fluorophenyl) cyclopenta-2,4-dienone and 0.8006g of TFDB (2.5mmol) were added to a 50ml round bottom flask under argon protection in a clean room, 7.8ml of dry DMF was added and dissolved by stirring, then 6 2.2212g (5mmol) of dianhydride monomer was added with a solid content of about 40% and reacted at 0 ℃ for 8h to obtain the corresponding PAA dope solution.

example 16:

in a clean room, under the protection of argon, 3,4-di ([1,1' -biphenyl ] -4-yl) -2,5-bis (4' -amino- [1,1' -biphenyl ] -4-yl) cyclopenta-2,4-dienone 4.3134(6mmol) was added to a 100ml three-necked flask equipped with a mechanical stirring device, 29.5ml of dry DMF was added, and after stirring to form a homogeneous solution, 6FDA2.6654g (6mmol) was added in four times, the solid content was about 20%, and the reaction was stirred at 0 ℃ for 8 hours to obtain the corresponding PAA dope solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as a volume ratio of 6:3:1, dropwise adding 6ml of the imidizing reagent into the PAA glue solution, and stirring at 80 ℃ to perform chemical imidization for 0.7 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 160 ℃ in an air drying oven, keeping the temperature for 0.6h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 360 ℃ and keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 17:

diamine 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophen-yl) cyclopenta-2,4-dienone 3.0134(5mmol) is added into a 100ml three-neck flask equipped with a mechanical stirring device in a clean room under the protection of argon, 12.2ml of dried dimethyl sulfoxide and 10ml of dried DMF are added, stirring is carried out to form a homogeneous solution, then 6FDA 2.2434g (5.05mmol) is added in portions, the solid content is about 20%, and the reaction is carried out for 8h under the condition of 0 ℃ to obtain the corresponding PAA glue solution.

And preparing an imidizing reagent by taking DMF (dimethyl formamide), pyridine and acetic anhydride as volume ratios of 3:3:1, adding 5ml of the imidizing reagent into the PAA glue solution, and stirring at 25 ℃ to perform chemical imidization for 1 hour. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 100 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 380 ℃, keeping the temperature for 5min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 18:

diamine 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4- (9, 9-dimethyl-9H-fluoro-2-yl) phenyl) cyclopenta-2,4-dienone 4.7562(5mmol) is added to a 100ml round bottom flask under argon protection in a clean room, 42.1ml dry DMF is added and stirred to form a homogeneous solution, then 6FDA 2.2656g (5.1mmol) is added in portions, the solid content is about 15%, and the reaction is stirred at 0 ℃ for 8H to obtain the corresponding PAA glue solution.

And preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as a volume ratio of 6:3:1, adding 8ml of imidizing reagent into the PAA glue solution, and stirring at 25 ℃ for chemical imidization for 1 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 120 ℃ in an air-blast drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃, keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 19:

diamine 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-methoxyphenyl) cyclopenta-2,4-dienone 1.2535(2mmol) was added to a 50ml flask under argon protection in a clean room, 9ml of dried DMF was added and stirred to form a homogeneous solution, and then 0.88g (1.98mmol) of 6FDA was added in portions with a solid content of about 20% and stirred at 5 ℃ for 20 hours to obtain the corresponding PAA colloidal solution.

An imidizing reagent is prepared by taking DMF (dimethyl formamide), acetic anhydride and pyridine (6: 3: 1) as volume ratios, 2ml of imidizing reagent is added into the PAA glue solution, and chemical imidization is carried out for 1h under stirring at 25 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1.5h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃, keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out a sample, and removing the PI film from the glass plate.

example 20:

diamine 2,5-bis (4'- (4-3,4-di ([1,1' -biphenol ] -4-yl) -2,5-bis (4'- (4-aminophenoxy) - [1,1' -biphenol ] -4-yl) cyclopenta-2,4-dienone 2.7093(3mmol) was added to a 50ml flask under argon protection in a clean room, 19.5ml of dried DMF was added and stirred to form a homogeneous solution, 1.3327g (3mmol) of 6FDA was added in four portions, the solid content was about 18%, and the reaction was stirred at 0 ℃ for 6 hours to obtain the corresponding PAA colloidal solution.

An imidizing reagent is prepared by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, 3.5ml of imidizing reagent is added into the PAA glue solution, and chemical imidization is carried out for 1h under stirring at 25 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 160 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 21:

diamine 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-hydroxyphenyl) cyclopenta-2,4-dienone 1.1974(2mmol) was added to a 50ml flask under argon protection in a clean room, 6.8ml of dry DMF was added and stirred to form a homogeneous solution, 0.9329g (2.1mmol) of 6FDA was added in three portions to obtain a solution with a solid content of about 25%, and the reaction was stirred at 0 ℃ for 5 hours to obtain the corresponding PAA colloidal solution.

An imidizing reagent is prepared by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, 1.5ml of imidizing reagent is added into the PAA glue solution, and chemical imidization is carried out for 1h under stirring at 25 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 160 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 22:

diamine 3,4-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -2,5-bis (4-nitrophenyl) cyclopenta-2,4-dienone 1.3134(2mmol) was added to a 50ml round bottom flask in a clean room under argon protection, 12ml of dry DMF was added and stirred to form a homogeneous solution, 0.8441g (1.9mmol) of 6FDA was added in three portions, the solid content was about 16%, and the reaction was stirred at 0 ℃ for 40 hours to obtain the corresponding PAA dope solution.

An imidizing reagent is prepared by taking DMF, acetic anhydride and pyridine as the volume ratio of 6:3:1, 2.5ml of imidizing reagent is added into the PAA glue solution, and chemical imidization is carried out for 1h under stirring at 25 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 23:

this example provides a method for synthesizing a black polyimide copolymer, which is prepared by copolymerizing two diamines, 2,5-bis (4'- (4-aminophenyl) - [1,1' -biphenyl ] -4-yl) -3,4-diphenylcyclopenta-2,4-dienone and ODA, with OPDA, wherein the amount of tetraphenylcyclopentadienone-containing diamine material in this example is 50% of the total diamine material.

1.8062g (2mmol) of 3,4-di ([1,1' -biphenyl ] -4-yl) -2,5-bis (4' - (4-aminophenyl) - [1,1' -biphenyl ] -4-yl) cyclopenta-2,4-dienone and 0.4005g of ODA (2mmol) were added to a 50ml round bottom flask under argon protection in a clean room, 17.8ml of dried DMAc was added, and after stirring and dissolving, 1.2409g (4mmol) of dianhydride monomer OPDA was added, the solid content was about 18%, and the reaction was carried out at 0 ℃ for 12 hours to obtain the corresponding PAA liquid cement.

An imidizing reagent is prepared by taking DMAc, acetic anhydride and triethylamine as volume ratio of 6:3:1, 3ml of imidizing reagent is dripped into PAA glue solution, and chemical imidization is carried out for 1h under stirring at 25 ℃. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 24:

this example provides a method for synthesizing a black PI copolymer, which is prepared by copolymerizing two diamines, 2,5-bis (4' -amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-methoxyphenylyl) cyclopenta-2,4-dienone and 4,4' -diaminodiphenyl sulfone, with 3,3',4,4' -diphenylsulfonyl tetracarboxylic dianhydride, wherein the amount of tetraphenylcyclopentadienone-containing diamine material in this example is 50% of the total diamine material.

1.2535g (2mmol) of 2,5-bis (4' -amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-methoxyphenyl) cyclopenta-2,4-dienone and 0.4966g of 4,4' -diaminodiphenyl sulfone (2mmol) were charged into a 50ml round bottom flask under argon protection in a clean room, 11.9ml of dried DMF was added and stirred to dissolve it, then 1.4311g (4mmol) of dianhydride monomer 3,3',4,4' -diphenylsulfonyl tetracarboxylic dianhydride was added and reacted at 0 ℃ for 24 hours to obtain the corresponding PAA dope solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 2ml of the imidizing reagent into PAA glue solution, and stirring at 25 ℃ for chemical imidization for 1 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 25:

this example provides a method for synthesizing a black polyimide copolymer, which is prepared by copolymerizing two diamines, 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and 3, 5-diaminobenzotrifluoride, with 6FDA, wherein the amount of tetraphenylcyclopentadienone-containing diamine substance is 50% of the total diamine substance.

1.2054g (2mmol) of 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and 0.3523g of 3, 5-diaminobenzotrifluoride (2mmol) were added to a 50ml round bottom flask under argon protection in a clean room, 8.2ml of dry DMF was added and dissolved by stirring, then dianhydride monomer 6FDA 1.777g (4mmol) was added and the solid content was about 30% and reacted at 0 ℃ for 6h to obtain the corresponding PAA colloidal solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 1.8ml of the imidizing reagent into PAA glue solution, and stirring at 25 ℃ for chemical imidization for 1 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 26:

this example provides a method for synthesizing black PI copolymer, which is prepared by copolymerizing 6FDA with two diamines of 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and 9, 9-bis (4-aminophenyl) fluorene, wherein the amount of tetraphenylcyclopentadienone-containing diamine substance is 50% of the total diamine substance.

1.2054g (2mmol) of 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone and 0.6969g of 9, 9-bis (4-aminophenyl) fluorene (2mmol) are added to a 50ml round bottom flask under argon protection in a clean room, 11.7ml of dried DMF is added, and after dissolving by stirring, 6FDA 1.777g (4mmol) of dianhydride monomer with a solid content of about 25% is added and reacted at 0 ℃ for 8h to obtain the corresponding PAA glue solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 2.1ml of the imidizing reagent into PAA glue solution, and stirring at 25 ℃ for chemical imidization for 1 h. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

example 27:

this example provides a method for synthesizing black PI copolymer, which is prepared by copolymerizing 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone with BTDA and 6FDA dianhydride.

2.4108g (4mmol) of 2,5-bis (4'-amino- [1,1' -biphenyl ] -4-yl) -3,4-bis (4-fluorophenyl) cyclopenta-2,4-dienone are added to a 50ml round bottom flask under argon protection in a clean room, 21.9ml of dry DMF is added and dissolved by stirring, then dianhydride monomer 6FDA 0.8885g (2mmol) and BTDA 0.6445g (2mmol) with a solid content of about 16% are added and reacted at 0 ℃ for 5h to obtain the corresponding PAA glue solution.

Preparing an imidizing reagent by taking DMF (dimethyl formamide), acetic anhydride and isoquinoline as volume ratios of 6:3:1, dropwise adding 4ml of the imidizing reagent into PAA glue solution, and stirring at 25 ℃ for chemical imidization for 1 hour. Scraping and coating the chemically imidized PI glue solution on a clean glass plate, heating to 150 ℃ in an air drying oven, keeping the temperature for 1h to remove the solvent, then transferring to a vacuum drying oven, quickly heating to 400 ℃ and keeping the temperature for 10min to fully imidize the PI film, then cooling to room temperature, taking out the sample and removing the PI film from the glass plate.

the black PI prepared in the examples 1 to 27 is tested for thermal property, mechanical property, visible light absorption property, electric breakdown strength and solubility property, and the results are shown in the following tables 1 and 2, and the testing method is as follows:

dynamic thermomechanical properties analysis (DMA): testing the glass transition temperature of PI by using a DMA Q850 type dynamic thermo-mechanical property analyzer of American TA company, performing position correction on a DMA instrument before testing, clamping a sample into a DMA clamp according to the specification of 20 multiplied by 6mm (length multiplied by width) in effective size, wherein the heating rate is 5 ℃/min, the testing temperature range is 25-450 ℃, the amplitude is 20 mu m, and the frequency is 1 Hz; and (3) testing mechanical properties: referring to GB/T16421-1996, a CMT6103 microcomputer control electronic universal tester of Xingsi Material detection Limited, Shenzhen is utilized to test the mechanical property of the PI film, the specification of a sample is 100mm multiplied by 10mm (length multiplied by width), the original distance of the sample is 50mm, the initial stretching rate is 2mm/min, when the elongation is 1mm, the stretching rate is increased to 20mm/min, each sample is tested for 5 times in parallel, and the results are averaged; ultraviolet-visible absorption spectrum (UV-vis): the method comprises the following steps of (1) researching the absorption capacity of the film on visible light by using a U-3900 ultraviolet-visible spectrophotometer of Hitachi corporation of Japan, wherein the test range is 200-800 nm, and the thickness of a PI film is about 20 mu m; measurement of electrical strength: the film insulation strength was measured using ZXIBV-2/10 breakdown voltage test system from Guilin Zymin detection Equipment, Inc. in an environment of 20 ℃ and 50% relative humidity. Different 5 sites were tested on a PI membrane and averaged. The voltage is 10kV, and the boosting speed is 0.5 kV/s. The solubility property test concentration is 10mg PI membrane is dissolved in 1mL solvent, and the solubility is divided into the following four types according to the dissolving degree of PI in turn: "+ +" indicates complete dissolution at room temperature and "+" indicates complete dissolution upon heating to 90 ℃. "+ -" indicates partial dissolution by heating to 90 deg.C, "-" indicates no dissolution by heating to 90 deg.C.

TABLE 1 physical Properties of intrinsic black PI synthesized in examples 1-27

TABLE 2 solubility of intrinsic black polyimides synthesized in examples 1 to 27

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An intrinsic black polyimide, characterized in that the structural formula of the polyimide is as follows:

wherein: m is 5-10000, n is 0-10000;

wherein R is₁Is any one of the following structural formulas:

R₂is any one of the following structural formulas:

wherein R is methyl, ethyl, propyl or butyl;

wherein Y is selected from one or more of the following structures:

2. the process for preparing an intrinsic black polyimide according to claim 1, comprising the steps of: in an inert gas atmosphere, dissolving a diamine monomer containing a tetraphenylcyclopentadienone structure in a polar aprotic solvent, adding a dianhydride monomer after the diamine monomer is completely dissolved, stirring and reacting for 2-48 h at-15-45 ℃ to obtain a homogeneous and viscous polyamic acid precursor glue solution, and then carrying out imidization and dehydration on the polyamic acid precursor to obtain the intrinsic black polyimide containing the tetraphenylcyclopentadienone structure.

3. The method of claim 2, wherein the amount ratio of diamine monomer to dianhydride monomer is 1: 0.9 to 1: 1.1.

4. The method for preparing intrinsic black polyimide according to claim 2, wherein the total mass of diamine monomer containing X and Y structures and dianhydride monomer containing Z structure accounts for 2-50% of the mass of polyamic acid glue solution.

5. The method for preparing intrinsic black polyimide according to claim 2, wherein the inert gas is one or more of nitrogen, helium and argon; the polar aprotic organic solvent is one or more of N-methylpyrrolidone, dimethyl sulfoxide, dimethyl sulfone, sulfolane, 1, 4-dioxane, N-dimethylacetamide, N-dimethylformamide, m-cresol and tetrahydrofuran.

6. The method of claim 2, wherein the polyamic acid precursor is dehydrated by thermal imidization or chemical imidization to obtain the polyimide.

7. The method for preparing intrinsic black polyimide according to claim 6, wherein the thermal imidization is performed by: firstly, uniformly coating the polyamic acid glue solution on a glass plate by scraping, then placing the glass plate in a vacuum oven for heating, wherein the temperature rise program is as follows: raising the temperature of the room temperature to 100 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 100 ℃ to 200 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 200 ℃ to 300 ℃, keeping the temperature for 0.2-1.5 h, raising the temperature from 300 ℃ to 350-500 ℃, keeping the temperature for 0.1-1 h, cooling, taking out the polyimide film, and peeling the polyimide film from the glass.

8. The method for preparing intrinsic black polyimide according to claim 6, wherein the specific operations of chemical imidization are: adding a dehydrating agent and a catalyst into the polyamic acid glue solution, stirring for 0.5-2 h at 0-100 ℃, then coating the glue solution on a glass plate, placing the glass plate into an oven, heating to 80-200 ℃, keeping the temperature for 0.2-2 h to remove the solvent, then carrying out vacuum high temperature to 320-450 ℃, keeping the temperature for 5-30 min to fully imidize, cooling, and then stripping the polyimide film from the glass plate.

9. The method of claim 8, wherein the dehydrating agent is acetic anhydride and the catalyst is pyridine, triethylamine, sodium acetate or isoquinoline.

10. The intrinsic black polyimide according to claim 1, wherein the intrinsic black polyimide is used in microelectronics, optoelectronics, military industry, and aerospace.