Polyimide material, colored polyamide acid precursor composition thereof and application of polyimide material in preparation of copolymerization type phthalocyanine colored polyimide film

Abstract

The invention provides a polyimide material, a colored polyamide acid precursor composition thereof and application of the polyimide material in preparation of a copolymerization type phthalocyanine colored polyimide film. The polyimide is formed by copolymerization of hexafluorodianhydride and biphenyl tetracarboxylic dianhydride according to a specific proportion. The corresponding polyamide acid precursor composition can be dissolved in a conventional polar aprotic solvent, and has excellent solution stability and film-forming property. After thermal imidization treatment, the obtained film shows high transparency, low chromaticity deviation and uniform and controllable light-color appearance while keeping 5% thermal weight loss temperature higher than 500 DEG C, and meets the application requirements of colorless or light-color high-performance polyimide. According to the material, the problem of serious yellowing caused by charge transfer in strong molecules of traditional aromatic polyimide is remarkably solved, processing convenience and thermal mechanical performance are both considered, and the material is particularly suitable for the high-end technical fields of flexible OLED display substrates, optoelectronic device packaging, transparent high-temperature-resistant coatings and the like.

Description

Technical Field

[0001] This invention belongs to the field of high-performance polymer materials technology, specifically relating to polyimide materials, their colored polyamic acid precursor compositions, and their application in the preparation of copolymerized phthalocyanine-colored polyimide films. Background Technology

[0002] Polyimide, as a high-performance polymer, occupies an irreplaceable position in fields such as flexible electronic displays, aerospace insulation, and microelectronic packaging due to its excellent thermal stability, mechanical strength, and chemical resistance. In many practical applications, materials are not only required to possess these fundamental properties, but also often need to be endowed with specific colors to meet the needs of optical shielding, visual identification, or functional filtering. Therefore, developing polyimide films that combine excellent comprehensive performance with stable and uniform coloring capabilities has become a continuously focusing technical issue in this field.

[0003] To achieve coloring of polyimide to meet the needs of marking, decoration, or functional filtering, especially in flexible displays and wearable electronic devices to achieve high saturation and high stability of red, blue, and green color patterns, existing technologies mainly rely on physical blending methods to introduce chromophores. Patent CN114164688A discloses a method for preparing colored PI films using inorganic pigment blending. This method is simple, but inorganic pigments are prone to agglomeration and sedimentation, leading to uneven color, and achieving basic dispersion requires energy-intensive equipment, increasing production costs. Patent CN116120605A discloses a method for preparing colored polyimide films by mixing dye molecules with soluble yellow polyimide; however, during long-term use, organic dye molecules are prone to thermal migration, volatilization, or aggregation, leading to color fading and poor stability, thus affecting device performance or lifespan.

[0004] Phthalocyanine compounds are considered ideal for achieving high-temperature stable coloring due to their extremely high thermal decomposition temperatures and vibrant colors. However, the core challenge in introducing them into PI systems lies in compatibility and dispersibility. Existing technologies often attempt to chemically modify phthalocyanines to improve their bonding with polymers, such as patent CN107587871A which uses aminosilanes to surface-graft phthalocyanines. However, these methods are complex and may alter the optical properties of the chromophores; essentially, they represent a passive adaptation and do not address the compatibility issue at the source of PI backbone design.

[0005] Therefore, developing a method for preparing colored polyimide films that can start from the molecular design source and precisely and quantitatively control the polymer backbone structure to achieve perfect matching with specific high-performance chromophores, thereby obtaining excellent processability, high thermal stability and excellent color performance, is a technological gap that needs to be filled in this field. Summary of the Invention

[0006] To address the inherent contradictions and performance bottlenecks in existing colored polyimide materials regarding processability, heat resistance, and long-term color stability, this paper presents a high-performance colored polyimide film and its preparation method. Starting from molecular backbone engineering, this method actively constructs a polymer microenvironment highly compatible with metal phthalocyanine chromophores through quantitative design of monomer ratios. This achieves a synergistic optimization and breakthrough balance of solubility, processability, high-temperature resistance, color uniformity, and color fastness, providing a superior colored substrate solution for high-end optoelectronic devices.

[0007] First, this invention protects a polyimide material, which is prepared by polymerization and imidization of a reaction system comprising the following monomers: (i) Primary dianhydride monomer; (ii) Second dianhydride monomer; (iii) Aromatic diamine monomers; Wherein, the first dianhydride monomer is a fluorinated dianhydride, and the second dianhydride monomer is a fluorine-free rigid dianhydride; the molar ratio of the first dianhydride monomer to the second dianhydride monomer is 1:4 to 1:1, preferably 1:3 to 1:1; more preferably 3:7 to 1:1, and most preferably 3:7; The ratio of the total molar amount of the first dianhydride monomer and the second dianhydride monomer to the molar amount of the aromatic diamine monomer is 0.95~1.05:1, preferably 0.98~1.02:1.

[0008] For the technical solution described above, a further preferred option is... The first dianhydride has one of the following structural formulas: , , , ; The second dianhydride has one of the following structural formulas: , , , ; The aromatic diamine monomer is selected from one of the following structural formulas: , , , , , , , ; For the technical solution described above, a further preferred embodiment is that the aromatic diamine monomer is selected from one of the following compounds: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,5-bis(trifluoromethyl)-1,4-phenylenediamine, 2-(trifluoromethyl)-1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, and p-phenylenediamine (PPD); most preferably, TFMB or PPD; wherein TFMB is suitable for applications requiring high solution processability, and PPD is suitable for applications requiring higher thermal stability. Within the formulation range of this invention, both can yield a blue colored film with a 5% thermogravimetric temperature > 500°C and a CIE color difference ΔE ≤ 2.

[0009] For the technical solution described above, a further preferred embodiment is that the first dianhydride monomer is 4,4'-(hexafluoroisopropene) diaphthalic anhydride (6FDA). For the technical solution described above, it is further preferred that the second dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA). On the other hand, this invention protects a colored polyamic acid precursor composition, which, after thermal imidization / chemical imidization, can be converted into the polyimide material described above. Both use the same monomer composition and ratio, thus exhibiting synergistically optimized thermal stability and optical properties. The colored polyamic acid precursor composition comprises: (a) Polyamic acid, which is copolymerized from the primary dianhydride monomer, the secondary dianhydride monomer and the aromatic diamine monomer described above; wherein: The first dianhydride monomer is a fluorinated dianhydride, and the second dianhydride monomer is a fluorine-free rigid dianhydride; the molar ratio of the first dianhydride monomer to the second dianhydride monomer is 1:(1~4), preferably 1:(2~3), and more preferably 3:7; The ratio of the total molar amount of the first dianhydride monomer and the second dianhydride monomer to the molar amount of the aromatic diamine monomer is 0.95~1.05:1, preferably 0.98~1.02:1; most preferably 1:1.

[0010] (b) Metal phthalocyanine compounds, the structural formula of which is shown in general formula I below:

[0011] I Wherein: substituents R1, R2, R3, and R4 contain 2 to 4 -NH2 groups; when the number of amino groups is less than 4, the remaining substituents are independently selected from -H, -Cl-C. 12 Alkyl, -C1-C 12One of alkoxy, -OH, -COOH, -SO3H, or -halogen (F, Cl, Br, or I); M is one of Co, Cu, Al, Fe, Zn, Ti, or Mo; (c) Polar aprotic organic solvents: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or at least one of sulfolane, m-cresol and HMPT; The molar amount of the metal phthalocyanine compound is 0.5-10% of the molar amount of the aromatic diamine monomer, and the composition is a homogeneous and stable castable solution.

[0012] For the technical solution described above, it is further preferred that the remaining substituents are each independently selected from -H, -C1–C6 alkyl (more preferably -C1–C4 alkyl), -C1–C6 alkoxy (more preferably -C1–C4 alkoxy), -COOH or -SO3H or halogen; more preferably, the remaining substituents are each independently selected from -H, -CH3, -OCH3 or -Cl.

[0013] For the technical solution described above, it is further preferred that the –NH2 is preferably located at the β position of the phthalocyanine ring, and more preferably, the metal phthalocyanine compound has a centrosymmetric structure, such as tetraaminophthalocyanine metal.

[0014] For the technical solution described above, more preferably, M is selected from Cu, Co or Zn; more preferably, Co.

[0015] For the technical solution described above, it is further preferred that the solid content of the colored polyamic acid precursor composition is 10-40 wt%, more preferably, the solid content is 15-30 wt%, and even more preferably, the solid content is 10-25 wt%.

[0016] On the other hand, the present invention protects a phthalocyanine-based high-performance colored polyimide film, which is prepared by imidization and film formation of the colored polyamic acid precursor composition described above.

[0017] The resulting polyimide film maintains excellent solution processability while also exhibiting high thermal stability (5% thermogravimetric temperature > 500°C) and low color deviation (CIE color difference ΔE ≤ 2), forming an optimal formulation window that balances processability, thermal performance, and optical performance. Specifically, when the molar ratio of the first dianhydride monomer to the second dianhydride monomer is controlled at 1:(1~4), a colored film with a 5% thermogravimetric temperature > 500°C and a CIE color difference ΔE ≤ 2 can be obtained, forming a feasible formulation window that meets basic application requirements. When the molar ratio is further limited to 1:(2~3) (more preferably 3:7), the film's overall performance reaches its optimal level, exhibiting a thermogravimetric temperature of 508~512°C and a color difference ΔE as low as 1.4~1.6, making it suitable for demanding applications such as high-end OLED displays.

[0018] For the technical solution described above, a further preferred embodiment is that the chromaticity coordinates of the colored polyimide film are located in the blue region of the CIE Lab color space, where L*≤55, a*≤10, b*≤-15, which is suitable for blue filtering applications in OLED display devices. More preferably: L* = 32~52.5, a* = -53~-13, b* = -46~-17.

[0019] This invention also provides a method for preparing a phthalocyanine-based high-performance colored polyimide film, comprising the following steps: S1. Under a protective atmosphere, an aromatic diamine monomer and a metal phthalocyanine compound are added to organic solvent I and stirred to dissolve or uniformly disperse them to obtain a mixed solution; wherein the organic solvent I is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or sulfolane, m-cresol and HMPT; S2. At -20~0℃, the first dianhydride monomer and the second dianhydride monomer are added sequentially to the above mixed solution, and the mixture is stirred for 12–24 hours to obtain a colored polyamic acid precursor solution. Polyimide films are prepared from the colored polyamic acid precursor solution using one of the following two imidization methods: Method 1: Chemical imidization, the specific steps are as follows: S3-1. Add a catalyst and a dehydrating agent to the polyamic acid precursor solution to perform chemical imidization, and obtain a polyimide solution after the reaction; add the polyimide solution to a poor solvent, purify it repeatedly, and then dry it in a vacuum oven to obtain polyimide; S3-2. The prepared polyimide is dissolved in organic solvent II, and after degassing and filtration, a uniform casting solution is obtained. The casting solution is coated onto a glass substrate by casting, and then placed in a temperature-controlled device. Under the protection of an inert atmosphere, heat treatment is carried out with a gradient temperature program, during which the solvent evaporates in a stepwise manner and the polymer is finally cured, thereby obtaining a smooth and uniform polyimide film. Method 2: Thermal imidization, the specific steps are as follows: S3-1'. The polyamic acid precursor solution is adjusted to a solid content of 10-40%, and after degassing and filtration, it is cast onto a glass substrate. S3-2'. Thermal imidization is carried out under an inert atmosphere using a gradient heating program: first, the temperature is increased to 80-120°C at 1-5°C / min and held at that temperature for 0.5-2 hours; then, the temperature is increased to 250-350°C at 1-3°C / min and held at that temperature for 0.5-2 hours to obtain the polyimide film. The catalyst used in the chemical imidization is selected from at least one of pyridine, triethylamine, and imidazole; the dehydrating agent is selected from at least one of acetic anhydride and propionic anhydride; the volume ratio of catalyst to dehydrating agent is 1:(2~5); the chemical imidization reaction temperature is 20~50℃; and the reaction time is 10~24 hours. The organic solvent II is the same type as the organic solvent I used in S1, and the undesirable solvent is selected from at least one of methanol, ethanol, and deionized water.

[0020] For the technical solution described above, it is further preferred that the inert atmosphere is carried out under a nitrogen or argon atmosphere.

[0021] This invention also provides the use of the polyimide material described above in the preparation of high-temperature resistant, solution-processable functional optical components.

[0022] More preferably, the uses include the use of polyimide materials in the preparation of flexible display substrates, blue optical filters, or spacecraft thermal control coatings. It is particularly suitable as a blue filter layer in OLED display devices, which include a substrate, an anode, an organic light-emitting layer, a cathode, and a phthalocyanine-based high-performance colored polyimide film as described above disposed in the light emission path.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves a precise balance between flexible fluorinated segments and rigid non-fluorinated segments at the molecular level, thereby creating a polyimide backbone platform with predictable and controllable performance from the source. This platform design itself simultaneously overcomes the inherent challenges of heat resistance, processability, and compatibility with functional components that are difficult to achieve in traditional polyimide materials. It fundamentally eliminates color unevenness, optical defects, and mechanical weaknesses caused by chromophore aggregation, providing a crucial molecular basis for obtaining films with vibrant colors and uniform performance. It provides a novel and universal molecular design foundation for the development of high-performance functional polyimide materials.

[0024] 2. This design not only ensures that the polymer, after being chemically imidized into polyimide, retains excellent resolubility in specific organic solvents, allowing for film formation via a resolution-casting process, but also guarantees that the final film obtained in this way possesses superior thermal stability. This reprocessability and high thermal reliability effectively overcome the limitations of traditional technical solutions where various properties are mutually restrictive.

[0025] 3. Based on the stable bonding and dispersion of chromophores in the optimized main chain, the resulting colored film exhibits superior colorfastness. The film boasts rich, uniform color and excellent transparency, avoiding dye migration or fading issues during heat treatment. The resulting film displays bright and uniform color with minimal color change under high temperature, low temperature, or UV irradiation conditions, demonstrating excellent long-term weather resistance and appearance retention. This ensures the product's aesthetic appeal and reliability over long-term use.

[0026] 4. The colored polyimide film of this invention exhibits excellent comprehensive performance and broad application prospects. This method is simple, requiring no complex modification of phthalocyanine; high-performance coloring can be achieved through a one-step copolymerization process, which is environmentally friendly and cost-effective. The resulting film combines excellent processability, high thermal stability, vibrant and long-lasting color, and good mechanical properties, demonstrating enormous application potential in flexible display substrates and cover plates, high-end flexible circuits, special protective coatings, and microelectronic packaging. Attached Figure Description

[0027] Figure 1 Thermogravimetric curves of the polyimide molecules prepared in Examples 1-4 are shown. Figure 2 Thermogravimetric curves of the polyimide molecules prepared in Comparative Example 1 and Comparative Example 2 are shown. Figure 3 Infrared spectra of the polyimide molecules prepared in Examples 1-4; Figure 4 The ultraviolet absorption spectrum of the polyimide molecule prepared in Example 1; Figure 5 The ultraviolet absorption spectrum of the polyimide molecules prepared in Example 2; Figure 6 The ultraviolet absorption spectrum of the polyimide molecules prepared in Example 3; Figure 7 The ultraviolet absorption spectrum of the polyimide molecule prepared in Example 4; Figure 8 The CIE color analysis spectra of the polyimide films in Examples 1-4 are shown. Figure 9 This is an image of the blue polyimide film prepared in Example 1. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0029] Example 1 This embodiment provides a method for preparing a blue high-performance polyimide film.

[0030] Under a nitrogen atmosphere, 1.45 g (4.75 mmol) of 2,2'-bis(trifluoromethyl)diaminobiphenyl (TFMB) and 10 mL of dried N,N-dimethylacetamide (DMAc) were added to a 50 mL three-necked flask equipped with a magnetic stirrer and stirred until completely dissolved. Then, 0.0631 g (0.1 mmol) of (4,4',4'',4'''-tetraaminophthalocyanine cobalt) powder was added to obtain a blue-green solution. The reaction solution was kept in an ice bath at a temperature of 0-5 °C. A mixed dianhydride consisting of 1.11 g (2.5 mmol) of 4,4'-(hexafluoroisopropene)phthalic anhydride (6FDA) and 0.805 g (2.5 mmol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 1:1) was added in three portions. After the addition was complete, the reaction continued for 24 h to obtain a dark blue, viscous polyamic acid (PAA) solution.

[0031] To the above PAA solution, 3 ml g of acetic anhydride (dehydrating agent) and 2.5 ml of pyridine (catalyst) were added sequentially, and a chemical imidization reaction was carried out at 25 °C for 24 h. The polyimide solution was dropwise added to anhydrous ethanol and stirred to precipitate polymer, forming a blue fibrous precipitate. After filtration, impurities and solvents were removed by Soxhlet extraction. The precipitate was dried in a vacuum oven at 50 °C for 24 h to obtain blue polyimide powder.

[0032] Thin film preparation: The above-mentioned polyimide powder was dissolved in DMAc to prepare a casting solution with a solid content of 30 wt%. The solution was stirred at 25°C until completely dissolved and then ultrasonically treated for 30 min to remove bubbles. The casting solution was cast onto a clean glass plate and placed in a programmable temperature oven. Under a nitrogen flow, the temperature was increased at a gradient of 5°C / min to 80°C and held for 1 h; then increased at 5°C / min to 120°C and held for 1.5 h; finally, increased at 5°C / min to 250°C and held for 2 h. After the program was completed, the temperature was allowed to cool naturally to room temperature. The glass plate was then immersed in water to peel off the film, revealing a deep blue transparent polyimide film.

[0033] A blue polyimide film was prepared. Its thermogravimetric analysis (TGA) indicated that the film's thermal decomposition temperature (T0) under a nitrogen atmosphere was [value missing]. d5% The temperature was 528℃. Fourier transform infrared spectroscopy (FT-IR) confirmed the formation of the characteristic imine ring structure of the polyimide. Colorimetric analysis showed that the chromaticity coordinates of the film were L*=32.5, a*=-37.3, b*=-23.9.

[0034] Example 2 The ratio of dianhydrides was adjusted to 0.888 g (2 mmol) 4,4'-(hexafluoroisopropene) dianhydride (6FDA) and 0.967 g (3 mmol) 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 2:3), and other conditions remained the same as in Example 1, to prepare a blue polyimide film.

[0035] TGA indicates that the molecule under a nitrogen atmosphere at T d5% The temperature was 520℃. FT-IR confirmed the formation of the characteristic imine ring structure of the polyimide. Colorimetric analysis showed that the chromaticity coordinates of the film were L*=40.9, a*=-41.4, b*=-20.9.

[0036] Example 3 The ratio of dianhydrides was adjusted to 0.666 g (1.5 mmol) 4,4'-(hexafluoroisopropene) dianhydride (6FDA) and 1.128 g (3.5 mmol) 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 3:7), and other conditions remained consistent with Example 1, to prepare a blue polyimide film.

[0037] TGA indicates that the molecule under a nitrogen atmosphere at T d5% The temperature was 516℃. FT-IR confirmed the formation of the characteristic imine ring structure of the polyimide. Colorimetric analysis showed that the chromaticity coordinates of the film were L*=52.5, a*=-52.3, b*=-16.8.

[0038] Example 4 Blue polyimide films were prepared by adding only 2.22 g (5 mmol) of 4,4'-(hexafluoroisopropene) diacid anhydride (6FDA) as a dianhydride monomer, while maintaining the same conditions as in Example 1. Thermogravimetric analysis (TGA) showed that the molecule's thermal decomposition temperature (T0) under nitrogen atmosphere was [missing value]. d5% The temperature was 512℃. FT-IR confirmed the formation of the characteristic imine ring structure of the polyimide. Colorimetric analysis showed that the chromaticity coordinates of the film were L*=35.2, a*=-12.1, b*=-45.3.

[0039] Comparative Example 1 The ratio of dianhydrides was adjusted to 0.444 g (1 mmol) 4,4'-(hexafluoroisopropene) dianhydride (6FDA) and 1.288 g (4 mmol) 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 1:4). Other conditions remained consistent with Example 1, and a TGA test was performed. The test showed that the molecule exhibited good TGA performance under a nitrogen atmosphere. d5% The temperature was 528℃. However, the resulting polyimide powder could not be dissolved in organic solvents, making coating tests impossible.

[0040] Comparative Example 2 The ratio of dianhydrides was adjusted to 0.222 g (0.5 mmol) 4,4'-(hexafluoroisopropene) diaphthalic anhydride (6FDA) and 1.45 g (4.5 mmol) 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 1:9). Other conditions remained consistent with Example 1. During the polyimide dissolution and film-forming step, the polyimide was insoluble in the organic solvent, making subsequent film-forming operations impossible. TGA analysis was performed on the molecule, yielding its T... d5% The temperature is 535℃.

[0041] Comparative Example 3 With only 1.61 g (5 mmol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) added as the dianhydride monomer, and other conditions kept consistent with Example 1, irreversible gelation of the reaction solution occurred during the solution polymerization step, and the viscosity increased sharply, making subsequent casting film formation impossible.

[0042] Comparative Example 4 Using pyromellitic dianhydride (PMDA) instead of BTDA, the dianhydride ratio was adjusted to 1.11 g (2.5 mmol) 4,4'-(hexafluoroisopropene) dianhydride (6FDA) and 0.545 g (2.5 mmol) 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (6FDA:BTDA molar ratio of 1:1) during copolymerization with 6FDA. Other conditions remained the same as in Example 1. During the solution polymerization step, the reaction solution underwent irreversible gelation, and the viscosity increased sharply, making subsequent casting film formation impossible.

[0043] Comparing Example 1 with Comparative Examples 3 and 4 confirms the necessity of specific dianhydride combinations. Comparative Examples 3 (BTDA) and 4 (PMDA / 6FDA) underwent irreversible gelation during the polymerization stage, making subsequent solution processing and film formation completely impossible. This indicates that using BTDA alone or replacing it with other conventional rigid dianhydrides leads to synthesis failure.

[0044] Compared with Comparative Examples 1 and 2, Example 1 clarified the lower limit of the dianhydride ratio required to achieve processability. While Comparative Examples 1 (6FDA:BTDA = 1:4) and 2 (6FDA:BTDA = 1:9) could complete polymerization to obtain polyimide powder, the products could not be dissolved in organic solvents for film formation. This contrasts sharply with the successful film formation in Examples 1-4, demonstrating that when the molar ratio of 6FDA is too low, the resulting polymer loses its solubility due to excessively rigid molecular chains and overly dense packing.

[0045] Examples 1, 2, 3, and 4 are compared to reveal the fine-tuning effect of the dianhydride ratio on the final properties of the film. As the 6FDA ratio increases from 30% to 100%, the thermal decomposition temperature (Td5%) of the film shows a regular change, while the color coordinates (L*, a*, b*) undergo a systematic shift, indicating that color saturation and hue can be precisely controlled.

[0046] Example 4, compared with Examples 1, 2, and 3, further demonstrates the advantages of copolymer modification. Although the pure 6FDA system has good processability, its performance in specific colors may differ from expectations. Examples 1-3, by introducing a specific proportion of BTDA, not only maintained high thermal stability without significantly sacrificing processability, but more importantly, achieved targeted optimization and enhancement of color performance, obtaining a comprehensive effect that cannot be achieved by a single component.

[0047] In summary, the technical solution provided by this invention, by employing a specific combination of 6FDA and BTDA dianhydrides and controlling their molar ratio within a specific preferred range, unexpectedly and synergistically solves the long-standing technical challenge in the field of high-performance colored polyimide where it is difficult to simultaneously achieve "high heat resistance", "solution processability" and "target color stability / adjustability".

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyimide material, characterized in that: It is prepared by polymerization and imidization of a reaction system comprising the following monomers: (i) Primary dianhydride monomer; (ii) Second dianhydride monomer; (iii) Aromatic diamine monomers; Wherein, the first dianhydride monomer is a fluorinated dianhydride, and the second dianhydride monomer is a fluorine-free rigid dianhydride; the molar ratio of the first dianhydride monomer to the second dianhydride monomer is 1:4 to 1:1; The ratio of the total molar amount of the first dianhydride monomer and the second dianhydride monomer to the molar amount of the aromatic diamine monomer is 0.95~1.05:

1.

2. The polyimide material according to claim 1, characterized in that: The first dianhydride has one of the following structural formulas: ， ， ， ； The second dianhydride has one of the following structural formulas: ， ， ， ； The aromatic diamine monomer is selected from one of the following structural formulas: ， ， ， ， ， ， ， 。 3. The polyimide material according to claim 1 or 2, characterized in that, The aromatic diamine monomer is selected from one of the following compounds: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,5-bis(trifluoromethyl)-1,4-phenylenediamine, 2-(trifluoromethyl)-1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, and p-phenylenediamine (PPD).

4. A colored polyamic acid precursor composition, characterized in that: The composition comprises: (a) Polyamic acid, which is copolymerized from the monomers used in claim 1: (i) Primary dianhydride monomer; (ii) Second dianhydride monomer; (iii) Aromatic diamine monomers; Wherein, the first dianhydride monomer is a fluorinated dianhydride, and the second dianhydride monomer is a fluorine-free rigid dianhydride; the molar ratio of the first dianhydride monomer to the second dianhydride monomer is 1:(1~4); The ratio of the total molar amount of the first dianhydride monomer and the second dianhydride monomer to the molar amount of the aromatic diamine monomer is 0.95~1.05:1; (b) Metal phthalocyanine compounds, the structural formula of which is shown in general formula I below: I Wherein: substituents R1, R2, R3, and R4 contain 2 to 4 -NH2 groups; when the number of amino groups is less than 4, the remaining substituents are independently selected from -H, -Cl-C. 12 Alkyl, -C1-C 12 One of alkoxy, -OH, -COOH, -SO3H, or -halogen; M is one of Co, Cu, Al, Fe, Zn, Ti, or Mo; (c) Polar aprotic organic solvents: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or at least one of sulfolane, m-cresol and HMPT; The molar amount of the metal phthalocyanine compound is 0.5 to 10% of the molar amount of the aromatic diamine monomer.

5. The colored polyamic acid precursor composition according to claim 4, characterized in that, The precursor composition has a solid content of 10 to 40 wt%.

6. A phthalocyanine-based high-performance colored polyimide film, characterized in that, It is prepared by imidization and film formation of the colored polyamic acid precursor composition according to claim 5.

7. The colored polyimide film according to claim 6, characterized in that, The film's chromaticity coordinates are located in the blue region of the CIELab color space, where L*≤55, a*≤10, and b*≤-15.

8. The method for preparing phthalocyanine-based high-performance colored polyimide films as described in claim 6, characterized in that, Includes the following steps: S1. Under a protective atmosphere, an aromatic diamine monomer and a metal phthalocyanine compound are added to organic solvent I and stirred to dissolve or uniformly disperse them to obtain a mixed solution; wherein the organic solvent I is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or sulfolane, m-cresol and HMPT; S2. At -20~0℃, the first dianhydride monomer and the second dianhydride monomer used in claim 1 are added sequentially to the above mixed solution, and the mixture is stirred for 12–24 hours to obtain a colored polyamic acid precursor solution. Polyimide films are prepared from the colored polyamic acid precursor solution using one of the following two imidization methods: Method 1: Chemical imidization, including the following steps: S3-1. Add a catalyst and a dehydrating agent to the polyamic acid precursor solution to perform chemical imidization, and obtain a polyimide solution after the reaction; add the polyimide solution to a poor solvent, purify it repeatedly, and then dry it in a vacuum oven to obtain polyimide; S3-2. The prepared polyimide is dissolved in organic solvent II, and after degassing and filtration, a uniform casting solution is obtained; the casting solution is coated onto a glass substrate by casting, and then placed in a programmable temperature control device; Under an inert atmosphere, heat treatment is carried out with a gradient heating program, during which the solvent evaporates in a stepwise manner and the polymer is finally cured, resulting in a smooth and uniform polyimide film. Method 2: Thermal imidization, including the following steps: S3-1'. The polyamic acid precursor solution is adjusted to a solid content of 10-40%, and after degassing and filtration, it is cast onto a glass substrate. S3-2'. Thermal imidization is carried out under an inert atmosphere using a gradient heating program: first, the temperature is increased to 80-120°C at 1-5°C / min and held at that temperature for 0.5-2 hours; then, the temperature is increased to 250-350°C at 1-3°C / min and held at that temperature for 0.5-2 hours to obtain the polyimide film. The catalyst used in the chemical imidization is selected from at least one of pyridine, triethylamine, and imidazole; the dehydrating agent is selected from at least one of acetic anhydride and propionic anhydride; the volume ratio of catalyst to dehydrating agent is 1:(2~5); the chemical imidization reaction temperature is 20~50℃; and the reaction time is 10~24 hours. The organic solvent II is the same type as the organic solvent I used in S1, and the undesirable solvent is selected from at least one of methanol, ethanol, and deionized water.

9. Use of the polyimide material as described in any one of claims 1-3 in the preparation of high-temperature resistant, solution-processable functional optical components.

10. The use according to claim 9, characterized in that, This includes the use of polyimide materials in the preparation of flexible display substrates, blue optical filters, or thermal control coatings for spacecraft.

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