A polyetherimide-ultraviolet absorber composite film, a preparation method and application thereof

Abstract

The application discloses a polyetherimide-ultraviolet absorber composite film and a preparation method and application thereof. The method comprises the following steps: adding an ultraviolet absorber containing a hydroxyl group into a diamine dispersion solution to obtain a composite solution; adding a bisphenol A type diether dianhydride into the composite solution in batches, stirring and reacting to prepare a composite sol; and preparing a composite film by using the composite sol, and performing imidization treatment on the composite film to prepare the polyetherimide-ultraviolet absorber composite film. In the method, the ultraviolet absorber containing the hydroxyl group is introduced, the ultraviolet absorber containing the hydroxyl group can form a hydrogen bond with the polyetherimide, the chain segment combination is more compact, and the molecular chain segment is increased, so that the relative movement of the chain segment is not prone to occurring at high temperature, and therefore the thermal stability is improved, meanwhile, the weather resistance of the composite material is improved. The method is simple in operation, efficient in reaction, and has wide application value.

Description

Technical Field

[0001] This invention belongs to the field of electrical energy storage material thin film development technology, and relates to a polyetherimide-ultraviolet absorber composite film, its preparation method and application. Background Technology

[0002] Polyetherimide (PEI) possesses excellent comprehensive properties due to its stable aromatic heterocyclic structure, particularly in high and low temperature resistance, dimensional stability, mechanical properties, and radiation resistance. It is amber in color and non-crystalline. Unlike many traditional thermosetting polyimides, PEI incorporates ether bonds (RORs) in its main chain, resulting in higher mechanical strength and the ability to operate continuously at higher temperatures. These ether bonds also provide flexibility, improving the polymer's melt flowability and processability, thus addressing the difficulty in processing polyimide materials. This has led to its widespread application in electronics, electrical appliances, and aerospace. As a polymer with rigid thermal imide rings, PEI can withstand high ambient temperatures (>200ºC), making it a potential candidate for energy storage polymer films. However, at high temperatures, PEI exhibits high conductivity losses, reducing its charge-discharge efficiency and limiting its application in high-temperature environments. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a polyetherimide-ultraviolet absorber composite film, its preparation method and application, thereby solving the technical problem that polyetherimide has high conductivity loss when used at high temperatures, which reduces its charge and discharge efficiency.

[0004] This invention is achieved through the following technical solution:

[0005] A method for preparing a polyetherimide-ultraviolet absorber composite film includes the following steps:

[0006] S1: Add a hydroxyl-containing ultraviolet absorber to a diamine dispersion to obtain a composite solution;

[0007] S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred to react, thus obtaining a composite sol;

[0008] S3: Prepare a composite film using the composite sol, and then perform an imidization treatment on the composite film to obtain the polyetherimide-ultraviolet absorber composite film.

[0009] Preferably, the diamine dispersion is prepared by dissolving 4,4'-diaminodiphenyl ether in a solvent to obtain the diamine dispersion; the molar ratio of the bisphenol A type diether dianhydride to the 4,4'-diaminodiphenyl ether is (1~1.01):1.

[0010] Preferably, the solvent is any one of N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0011] Preferably, the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and / or 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole.

[0012] Preferably, the ultraviolet absorber accounts for 0.2% to 1% of the total mass of the 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

[0013] Preferably, in step S2, the reaction is stirred for 2-3 hours.

[0014] Preferably, in step S3, before imidizing the composite film, the composite film is dried, specifically at a drying temperature of 80~100℃ and a drying time of 6~12h.

[0015] Preferably, in step S3, when preparing the composite film using the composite sol, the thickness of the resulting composite film is 7~13μm.

[0016] A polyetherimide-ultraviolet absorber composite film is prepared by the method described above; the composite film has a breakdown field strength of 470~720 MV / m at 150°C. -1 .

[0017] The above-mentioned polyetherimide-ultraviolet absorber composite film is used in high-temperature energy storage.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] This invention discloses a method for preparing a polyetherimide-ultraviolet absorber composite film. The method involves introducing a hydroxyl-containing ultraviolet absorber, which can form hydrogen bonds with polyetherimide. Specifically, the hydroxyl groups in the ultraviolet absorber form hydrogen bonds with the oxygen in the diamine segments of PEI, resulting in tighter chain bonding and increased molecular chain length. This reduces the likelihood of relative chain movement at high temperatures, thereby improving thermal stability. Furthermore, the ultraviolet absorber can absorb ultraviolet light bands in the natural environment that significantly damage organic matter during aging, thus enhancing the weather resistance of the composite material. Simultaneously, the dielectric constant and conductivity of the ultraviolet absorber are similar to those of PEI, preventing electric field distortion and effectively improving the high-temperature resistance and weather resistance of polyetherimide.

[0020] Furthermore, another inventive aspect of this invention is the preparation process of the diamine dispersion, which involves dissolving 4,4'-diaminodiphenyl ether in a solvent to obtain the diamine dispersion; the molar ratio of the bisphenol A type diether dianhydride to the 4,4'-diaminodiphenyl ether is (1~1.01):1. Firstly, a molar ratio close to 1:1 ensures that the stoichiometry between the reactants is close to ideal, which is beneficial for the uniformity of the polymerization reaction and avoids excessive impurities caused by residual reactants, thus preventing them from affecting the performance of subsequent products. A slight excess of bisphenol A type diether dianhydride (1~1.01 times) can compensate for the loss of 4,4'-diaminodiphenyl ether due to volatilization, decomposition, or incomplete reaction during the reaction, thereby ensuring the reaction is as complete as possible. Additionally, a near-stoichiometric reaction helps to generate polyetherimides with uniform structure and narrow molecular weight distribution, which is crucial for improving the mechanical properties, thermal stability, and weather resistance of the composite film. Meanwhile, excessive bisphenol A diether dianhydride can promote chain growth to some extent, but too much can lead to excessive crosslinking, affecting the processing performance and final properties of the film.

[0021] Furthermore, the solvent is any one of N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Firstly, these three solvents are all strongly polar solvents, exhibiting excellent solubility for many organic compounds, especially those containing amino or amide functional groups. Therefore, they can effectively dissolve diamine monomers such as 4,4'-diaminodiphenyl ether (ODA) to form a stable diamine dispersion, providing favorable conditions for subsequent polymerization reactions. Secondly, during the polymerization reaction, these three solvents all possess good thermal stability, maintaining stable chemical properties at high temperatures and preventing impurities or product quality issues due to thermal decomposition.

[0022] Furthermore, another inventive aspect of this invention is that the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and / or 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole (UV-327). Firstly, both of these benzotriazole compounds are highly efficient ultraviolet absorbers, capable of strongly absorbing ultraviolet light (especially the UV-A and UV-B bands), thereby effectively preventing ultraviolet light from damaging the polyetherimide material. This absorption capacity helps improve the weather resistance and durability of the composite film. Additionally, this compound exhibits high thermal stability, maintaining its structural and performance stability at high temperatures, which is particularly important for polyetherimide, a material that requires processing and use at high temperatures. The ultraviolet absorber contains functional groups such as hydroxyl groups, which can form hydrogen bonds with the diamine segments in the polyetherimide, thereby enhancing compatibility and bonding with the matrix material. This compatibility helps improve the overall performance and stability of the composite film. The dielectric constant and conductivity of these UV absorbers are similar to those of polyetherimide, so their addition will not significantly change the electrical properties of the material, avoiding problems such as electric field distortion, effectively improving the high temperature resistance and weather resistance of polyetherimide, and enabling the composite film to maintain excellent overall performance.

[0023] Furthermore, another inventive aspect of this invention is that the ultraviolet absorber accounts for 0.2% to 1% of the total mass of the 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride. Firstly, within this range, the ultraviolet absorber can effectively exert its performance without affecting the properties of the polyetherimide material. Excessive ultraviolet absorber can lead to phase separation in the composite film, affecting the uniformity and stability of the material. However, within this addition range, the ultraviolet absorber can be uniformly dispersed in the polyetherimide matrix, avoiding phase separation. Additionally, an appropriate amount of ultraviolet absorber will not negatively affect the processing performance of the composite film; on the contrary, it may help improve the material's flowability, reduce processing temperature, etc., thereby improving processing efficiency and product quality.

[0024] Furthermore, another inventive aspect of this invention is that in step S2, the reaction is stirred for 2-3 hours. Firstly, this 2-3 hour stirring provides sufficient time for the reactants to fully contact and react. During this period, the polycondensation reaction between bisphenol A type diether dianhydride (such as BPADA) and 4,4'-diaminodiphenyl ether (ODA) can proceed relatively completely, forming high-molecular-weight polyetherimide. Simultaneously, the ultraviolet absorber can also be uniformly dispersed in the reaction system during this time, forming a stable bond with the polyetherimide segments. Secondly, sufficient stirring time helps reduce local concentration differences and temperature gradients in the reaction system, making the reaction more uniform. This contributes to the formation of polyetherimide with a uniform structure and narrow molecular weight distribution, thereby improving the mechanical properties, thermal stability, and weather resistance of the composite film. In addition, uniform stirring also reduces the formation of by-products, improving the purity and quality of the product.

[0025] Furthermore, another inventive aspect of this invention is that in step S3, before imidizing the composite film, the composite film is dried. Specifically, the drying temperature is 80~100°C, and the drying time is 6~12 hours. First, the drying treatment can effectively remove residual solvents from the film, preventing solvents from evaporating or remaining during the subsequent imidization process. The drying treatment can also remove moisture and solvents from the film, making the molecular chains of the film more tightly arranged, thereby improving the mechanical properties of the film. At the same time, the drying treatment ensures that the film is in a dry state before entering the imidization furnace, which is conducive to the smooth progress of the imidization reaction. In addition, the appropriate drying temperature (80~100°C) can also preheat the film, reducing thermal stress when entering the high-temperature imidization environment and preventing the film from deforming or cracking.

[0026] Furthermore, another inventive aspect of this invention is that in step S3, when preparing the composite film using the composite sol, the thickness of the resulting composite film is 7-13 μm. Firstly, setting the film thickness within the range of 7-13 μm ensures that the ultraviolet absorber is uniformly distributed within the film and effectively absorbs ultraviolet light. This thickness range guarantees sufficient ultraviolet absorption capacity while avoiding excessive thickness that would lead to light scattering and decreased transmittance, thereby optimizing the film's optical properties. Secondly, a thickness range of 7-13 μm ensures sufficient film strength while maintaining good flexibility and processability. Such a film is less prone to cracking or deformation during subsequent processing and use, improving the product's durability and reliability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating the preparation process of the polyetherimide-ultraviolet absorber composite material of the present invention.

[0029] Figure 2 The images show cross-sectional SEM comparisons of the polyetherimide-UV-327 composite film prepared in Example 6 of this invention and the polyetherimide film prepared in Comparative Example 1. (a) is an SEM image of the polyetherimide-UV-327 composite film at a scale bar of 5 μm; (b) is an SEM image of the polyetherimide-UV-327 composite film at a scale bar of 10 μm; (c) is an SEM image of the polyetherimide film at a scale bar of 5 μm; and (d) is an SEM image of the polyetherimide film at a scale bar of 10 μm.

[0030] Figure 3 The FT-IR spectra of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 are shown, where (a) and (b) represent different wavenumber ranges.

[0031] Figure 4 XPS spectra of the polyetherimide-UV-327 composite film prepared in Example 6 of the present invention and the polyetherimide film prepared in Comparative Example 1 are shown, where (a) is the full spectrum, (b) is the C fine spectrum, (c) is the O fine spectrum, and (d) is the N fine spectrum.

[0032] Figure 5 The Tauc diagrams are of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1.

[0033] Figure 6 The breakdown field strength Weibull distribution diagrams of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 25°C are shown.

[0034] Figure 7 The breakdown field strength Weibull distribution diagrams of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 150°C are shown.

[0035] Figure 8The dielectric constant (a) and frequency dependence of dielectric loss (b) of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 are shown.

[0036] Figure 9 The energy storage density and energy storage efficiency of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 25°C.

[0037] Figure 10 The energy storage density and energy storage efficiency of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 150°C are shown. Detailed Implementation

[0038] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0039] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0040] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0041] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0042] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0043] like Figure 1 As shown, a method for preparing a polyetherimide-ultraviolet absorber composite film includes the following steps:

[0044] S1: Add a hydroxyl-containing ultraviolet absorber to a diamine dispersion to obtain a composite solution;

[0045] The diamine dispersion is prepared by dissolving 4,4'-diaminodiphenyl ether in a solvent to obtain the diamine dispersion; the molar ratio of the bisphenol A type diether dianhydride to the 4,4'-diaminodiphenyl ether is (1~1.01):1.

[0046] The solvent is any one of N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0047] The ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and / or 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole.

[0048] The ultraviolet absorber accounts for 0.2% to 1% of the total mass of the 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

[0049] The molecular structural formulas of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole are as follows:

[0050] and

[0051] S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred for 2-3 hours to obtain a composite sol;

[0052] The general molecular structural formula of 4,4'-diaminodiphenyl ether is: ,

[0053] The general molecular structural formula of bisphenol A type diether dianhydride is: .

[0054] S3: Prepare a composite film with a thickness of 7~13μm using the composite sol, dry the composite film at 80~100℃ for 6~12h, and perform gradient temperature treatment on the composite film between 150~300℃, with each temperature treatment lasting 50min~1h, to complete the imidization process and obtain the polyetherimide-ultraviolet absorber composite film.

[0055] Furthermore, this invention also discloses a polyetherimide-ultraviolet absorber composite film prepared using the above method. In this composite film, the ultraviolet absorber improves the thermal stability and weather resistance of the novel polyetherimide, avoiding the electric field distortion problem caused by the mismatch between dielectric constant and conductivity resulting from the addition of inorganic fillers for modification. PEIs with different doping components all exhibit a higher dielectric constant than the original PEI at varying operating frequencies. ε r ) and significantly suppressed dielectric loss ( tanδ ) ， The composite material with 1% UV-327 added at room temperature (25ºC) and at high temperature (150ºC) exhibits a breakdown field strength as high as 783 MV.m. -1 and 721 MV.m -1 And 460 MV.m at 150℃ -1 It can still maintain an ultra-high energy storage efficiency of 90% under the field strength, which far exceeds that of pure polyetherimide materials. It has now been proven that it has achieved the goal of improving its energy storage efficiency and density, which is of great significance for promoting the application of polyetherimide.

[0056] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0057] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0058] Example 1

[0059] (1) Preparation of diamine dispersion

[0060] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0061] (2) Preparation of mixed solution

[0062] At room temperature, 0.0111 g of UV-327 was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0063] (3) Preparation of polyamic acid sol

[0064] Under ice-water bath conditions, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in four portions, with 1 g, 1 g, 1 g, and 1.0196 g added each time. After each addition, the mixture was stirred with external shear force for 30 min, 30 min, 30 min, and 1 h to obtain polyether ammonium acid sol.

[0065] (4) Preparation of polyetherimide-UV-327 composite film

[0066] A 10μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0067] (5) Thermal imidization treatment

[0068] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide-UV-327 composite film was obtained.

[0069] (6) Bubble membrane

[0070] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0071] Example 2

[0072] (1) Preparation of diamine dispersion

[0073] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0074] (2) Preparation of mixed solution

[0075] At room temperature, 0.0277 g of UV-327 was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0076] (3) Preparation of polyamic acid sol

[0077] Under ice-water bath conditions, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in four portions, with 1 g, 1 g, 1 g, and 1.0196 g added each time. After each addition, the mixture was stirred with external shear force for 30 min, 30 min, 30 min, and 1 h to obtain polyether ammonium acid sol.

[0078] (4) Preparation of polyetherimide-UV-327 composite film

[0079] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0080] (5) Thermal imidization treatment

[0081] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, a preliminary polyetherimide-UV-327 composite film was obtained.

[0082] (6) Bubble membrane

[0083] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0084] Example 3

[0085] (1) Preparation of diamine dispersion

[0086] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0087] (2) Preparation of mixed solution

[0088] Under ice-water bath conditions, 0.0558g of UV-327 was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0089] (3) Preparation of polyamic acid sol

[0090] At room temperature, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in four portions, with 1 g, 1 g, 1 g, and 1.0196 g added each time. After each addition, the mixture was stirred with external shear force for 30 min, 30 min, 30 min, and 1 h to obtain a polyether ammonium acid sol.

[0091] (4) Preparation of polyetherimide-UV-327 composite film

[0092] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0093] (5) Thermal imidization treatment

[0094] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide-UV-327 composite film was obtained.

[0095] (6) Bubble membrane

[0096] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0097] Example 4

[0098] (1) Preparation of diamine dispersion

[0099] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0100] (2) Preparation of mixed solution

[0101] At room temperature, 0.0111 g of UV-327 was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0102] (3) Preparation of polyamic acid sol

[0103] Under ice-water bath conditions, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in seven portions: 1 g, 1 g, 1 g, 0.25 g, 0.25 g, 0.25 g, and 0.2696 g, respectively. After each addition, the mixture was stirred under applied shear force for 30 min, 30 min, 30 min, 10 min, 10 min, 10 min, and 1 h to obtain the polyether ammonium acid sol.

[0104] (4) Preparation of polyetherimide-UV-327 composite film.

[0105] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0106] (5) Thermal imidization treatment

[0107] The scraped film was placed in a medium-high temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide-UV-327 composite film was obtained.

[0108] (6) Bubble membrane

[0109] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0110] Example 5

[0111] (1) Preparation of diamine dispersion

[0112] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0113] (2) Preparation of mixed solution

[0114] At room temperature, 0.0277 g of UV-327 absorber was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0115] (3) Preparation of polyetheramic acid sol

[0116] Under ice-water bath conditions, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in seven portions: 1 g, 1 g, 1 g, 0.25 g, 0.25 g, 0.25 g, and 0.2696 g, respectively. After each addition, the mixture was stirred under applied shear force for 30 min, 30 min, 30 min, 10 min, 10 min, 10 min, and 1 h to obtain the polyether ammonium acid sol.

[0117] (4) Preparation of polyetherimide-UV-327 composite film

[0118] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0119] (5) Thermal imidization treatment

[0120] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide-UV-327 composite film was obtained.

[0121] (6) Bubble membrane

[0122] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0123] Example 6

[0124] (1) Preparation of diamine dispersion

[0125] The molar ratio of ODA to BPADA was 1:1. At room temperature, 1.5 g of 4,4-diaminodiphenyl ether (ODA) was added to 18.6 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0126] (2) Preparation of mixed solution

[0127] At room temperature, 0.0558 g of UV-327 was added to (1), and the mixture was sonicated for 10 min to obtain a homogeneous solution.

[0128] (3) Preparation of polyamic acid sol

[0129] Under ice-water bath conditions, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in seven portions: 1 g, 1 g, 1 g, 0.25 g, 0.25 g, 0.25 g, and 0.2696 g, respectively. After each addition, the mixture was stirred under applied shear force for 30 min, 30 min, 30 min, 10 min, 10 min, 10 min, and 1 h to obtain the polyether ammonium acid sol.

[0130] (4) Preparation of polyetherimide-UV-327 composite film

[0131] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0132] (5) Thermal imidization treatment

[0133] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide-UV-327 composite film was obtained.

[0134] (6) Bubble membrane

[0135] After cooling, the glass plate with the polyetherimide-UV-327 composite film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide-UV-327 composite film.

[0136] Comparative Example 1

[0137] (1) Preparation of diamine dispersion

[0138] The molar ratio of ODA to BPADA is 1:1. Under room temperature conditions, 1.5 g of 4,4-diaminodiphenyl ether (ODA) is added to 18.5 ml of N,N-dimethylformamide (DMF) solvent and sonicated for 5 min to obtain a diamine dispersion.

[0139] (2) Preparation of polyamic acid sol

[0140] At room temperature, a total of 4.0196 g of bisphenol A diether dianhydride (BPADA) was added to the diamine dispersion in four portions, with each addition being 1 g, 1 g, 1 g, and 1.0196 g, respectively. After each addition, the mixture was stirred under applied shear force for 30 min, 30 min, 30 min, and 1 h to obtain a polyether ammonium acid sol.

[0141] (4) Preparation of polyetherimide film

[0142] A 10 μm film is created by coating one side of a glass plate with polyamic acid sol using a casting method and then scraping it out with a scraper.

[0143] (5) Thermal imidization treatment

[0144] The scraped film was placed in a high-temperature oven and heated in stages. It was treated at 80℃ for 12 hours, and then at 150℃, 200℃, 250℃ and 300℃ for 1 hour each. After cooling, polyetherimide film was obtained.

[0145] (6) Bubble membrane

[0146] After cooling, the glass plate with the polyetherimide film is placed in hot water. Once the film falls off, it is wiped dry to obtain a smooth polyetherimide film.

[0147] Figure 2 The image shows a cross-sectional SEM comparison between the polyetherimide-UV-327 composite film prepared in Example 6 of this invention and the polyetherimide film prepared in Comparative Example 1. As can be seen from the image, the cross-section of the polyetherimide-UV-327 composite film is smoother, indicating that the composite film has a denser internal structure than the PEI film and has better stability at high temperatures, thereby improving the energy storage performance at high temperatures, especially the electrical breakdown performance.

[0148] Figure 3The figures show the FT-IR spectra of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1. As can be seen from the figures, the peak value is 2000 cm⁻¹. -1 The peak position shifts to the right at the left and right positions. This is due to the increase in the bond length of the large π bond on the benzene ring, which weakens the π-π stacking. The weakening of the π-π stacking of the benzene ring reduces the inter-chain electron transfer caused by the π-π stacking between the composite material chains, thereby reducing leakage current and improving the charge and discharge efficiency at high temperatures.

[0149] Figure 4 The figures show the fine XPS spectra of the polyetherimide-UV-327 composite film prepared in Example 6 of this invention and the polyetherimide film prepared in Comparative Example 1. As can be seen from the figures, the peak position shifted to the left in the fine XPS spectra of oxygen. Due to the increase in oxidation state, the binding energy increases, and there is a tendency to lose electrons. Therefore, the O on the ODA segment in the PEI chain forms an OH-O hydrogen bond with the hydroxyl group on UV-327. The generation of this crosslinking structure makes the structure of the polyetherimide-UV-327 composite film more stable.

[0150] Figure 5 The images show the UV-Vis spectra of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1. As can be seen from the images, the polyetherimide-UV-327 composite film has a larger band gap, indicating that the composite material has stronger electrical insulation properties and therefore better electrical breakdown performance at high temperatures.

[0151] Figure 6 The breakdown field strength Weibull distribution diagrams at 25°C are shown for the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1. Figure 7 The diagram shows the breakdown field strength Weibull distribution of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 150°C. As can be seen from the diagram, the breakdown strength of the polyetherimide-UV-327 composite film is higher, which is mainly attributed to the tighter inter-chain bonding and larger optical band gap of the composite material.

[0152] In addition, Table 1 shows the breakdown strength of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of the present invention and the polyetherimide film prepared in Comparative Example 1 at 25°C. As can be seen from Table 1, the composite material has a tighter inter-chain bond, a larger optical band gap, and a higher breakdown strength.

[0153]

[0154] Table 2 compares the breakdown strength of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention with that of the polyetherimide film prepared in Comparative Example 1 at 150°C. As can be seen from Table 2, the composite film has better electrical breakdown performance at high temperature.

[0155]

[0156] Figure 8 The figure shows the frequency dependence of dielectric constant (a) and dielectric loss (b) of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1. As can be seen from the figure, the polyetherimide-UV-327 composite film has a higher dielectric constant and a lower dielectric loss.

[0157] Figure 9 The energy storage density and energy storage efficiency of the polyetherimide-UV-327 composite films prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 25°C are compared. Figure 10 The figures show the energy storage density and energy storage efficiency of the polyetherimide-UV-327 composite film prepared in Examples 4-6 of this invention and the polyetherimide film prepared in Comparative Example 1 at 150°C. As can be seen from the figures, the polyetherimide-UV-327 composite film has higher energy storage efficiency and density, which is mainly due to the tight inter-chain structure and reduced inter-chain electron transfer.

[0158] Example 7

[0159] A method for preparing a polyetherimide-ultraviolet absorber composite film includes the following steps:

[0160] S1: The diamine dispersion is obtained by dissolving 4,4'-diaminodiphenyl ether in a solvent. A UV absorber containing hydroxyl groups is added to the diamine dispersion to obtain a composite solution. The solvent is N,N-dimethylformamide. The UV absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0161] S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred for 3 hours to obtain a composite sol; the molar ratio of bisphenol A type diether dianhydride to 4,4'-diaminodiphenyl ether is 1.01:1. The ultraviolet absorber accounts for 0.2% of the total mass of 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

[0162] S3: A composite film with a thickness of 7 μm is prepared using the composite sol. The composite film is dried at 100°C for 12 h, and then subjected to gradient temperature treatment between 150 and 300°C, specifically at 150°C, 200°C, 250°C, and 300°C for 50 min to 1 h respectively, to complete the imidization process and obtain the polyether imide-ultraviolet absorber composite film.

[0163] Example 8

[0164] A method for preparing a polyetherimide-ultraviolet absorber composite film includes the following steps:

[0165] S1: 4,4'-Diaminodiphenyl ether is dissolved in a solvent to obtain the diamine dispersion. A UV absorber containing hydroxyl groups is added to the diamine dispersion to obtain a composite solution. The solvent is dimethylacetamide. The UV absorber is 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole.

[0166] S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred for 3 hours to obtain a composite sol; the molar ratio of bisphenol A type diether dianhydride to 4,4'-diaminodiphenyl ether is 1.01:1. The ultraviolet absorber accounts for 1% of the total mass of 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

[0167] S3: A composite film with a thickness of 13 μm is prepared using the composite sol. The composite film is dried at 100°C for 6 hours and subjected to gradient temperature treatment between 150°C and 300°C, specifically treated at 150°C, 200°C, 250°C, and 300°C for 1 hour each to complete the imidization process and obtain the polyether imide-ultraviolet absorber composite film.

[0168] Example 9

[0169] A method for preparing a polyetherimide-ultraviolet absorber composite film includes the following steps:

[0170] S1: The diamine dispersion is obtained by dissolving 4,4'-diaminodiphenyl ether in a solvent. A UV absorber containing hydroxyl groups is added to the diamine dispersion to obtain a composite solution. The solvent is N-methylpyrrolidone. The UV absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0171] S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred for 2.5 h to obtain a composite sol; the molar ratio of bisphenol A type diether dianhydride to 4,4'-diaminodiphenyl ether is 1.01:1. The ultraviolet absorber accounts for 0.7% of the total mass of 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

[0172] S3: A composite film with a thickness of 10 μm is prepared using the composite sol. The composite film is dried at 90°C for 10 h, and then subjected to gradient temperature treatment between 150 and 300°C, specifically at 150°C, 200°C, 250°C, and 300°C for 55 min each, to complete the imidization process and obtain the polyether imide-ultraviolet absorber composite film.

[0173] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0174] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a polyetherimide-ultraviolet absorber composite film, characterized in that, Includes the following steps: S1: Add a UV absorber containing hydroxyl groups to a diamine dispersion to obtain a composite solution; S2: Bisphenol A type diether dianhydride is added to the composite solution in batches and stirred to react, thus obtaining a composite sol; S3: Prepare a composite film using the composite sol, and then perform an imidization treatment on the composite film to obtain the polyetherimide-ultraviolet absorber composite film; The diamine dispersion is prepared by dissolving 4,4'-diaminodiphenyl ether in a solvent to obtain the diamine dispersion; the molar ratio of the bisphenol A type diether dianhydride to the 4,4'-diaminodiphenyl ether is (1~1.01):

1. The ultraviolet absorber accounts for 0.2% to 1% of the total mass of the 4,4'-diaminodiphenyl ether and bisphenol A type diether dianhydride.

2. The method for preparing a polyetherimide-ultraviolet absorber composite film according to claim 1, characterized in that, The solvent is any one of N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

3. The method for preparing a polyetherimide-ultraviolet absorber composite film according to claim 1, characterized in that, The ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and / or 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole.

4. The method for preparing a polyetherimide-ultraviolet absorber composite film according to claim 1, characterized in that, In step S2, the reaction is stirred for 2-3 hours.

5. The method for preparing a polyetherimide-ultraviolet absorber composite film according to claim 1, characterized in that, In step S3, before imidizing the composite film, the composite film is dried. Specifically, the drying temperature is 80~100℃ and the drying time is 6~12h.

6. The method for preparing a polyetherimide-ultraviolet absorber composite film according to claim 1, characterized in that, In step S3, when preparing the composite film using the composite sol, the thickness of the resulting composite film is 7~13μm.

7. A polyetherimide-ultraviolet absorber composite film, characterized in that, The composite film is prepared by the method described in any one of claims 1 to 6; the breakdown field strength of the composite film at 150°C is 470~720 MV / m. -1 .

8. The application of the polyetherimide-ultraviolet absorber composite film as described in claim 7 in high-temperature energy storage.

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