Hydrophobically modified heterocyclic aramid-based insulating film, preparation method and application

Abstract

The invention relates to the technical field of preparation of insulating materials, in particular to a hydrophobic modified heterocyclic aramid-based insulating film, a preparation method and application. According to the method, a heterocyclic aramid polymer with high breakdown strength and high heat resistance is prepared to serve as a base material, hydrophobic long-chain alkane is grafted through active sites on imidazole of heterocyclic aramid, and the hydrophobic modified heterocyclic aramid-based insulating film is obtained. The heterocyclic aramid is endowed with hydrophobic performance on the basis of flame retardance, temperature resistance, excellent mechanical strength and high breakdown strength of the heterocyclic aramid, and the high-strength, high-modulus, heat-resistant and hydrophobic heterocyclic aramid-based insulating film is successfully prepared. The insulating property of the film is doubly enhanced under the action of imidazole in the film and the assistance of a surface hydrophobic function, and the method is simple and has important significance in application of the heterocyclic aramid insulating material in complex scenes. The problems of poor hydrophobicity and insulativity of a heterocyclic aramid film in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the technical field of insulating material preparation, and in particular to a hydrophobically modified heterocyclic aramid-based insulating film, a preparation method and application thereof. Background Art

[0002] Aromatic polyamides are copolymerized from two monomers, namely 1,4-phenylenediamine and terephthaloyl chloride, to obtain aromatic II resins, namely para-aramid and meta-aramid. Aromatic II resins have the advantages of high tensile strength and good insulation performance, as well as good film-forming properties. Their paper-based materials have excellent comprehensive performance and are widely used in the field of high-performance insulation materials.

[0003] Heterocyclicaramid (HA) is a material formed by copolymerizing para-aramid with a diamine containing benzimidazole as the third monomer. Due to its special heteroaromatic ring structure, its mechanical tensile strength is higher than that of para-aramid material, and it is widely used in the aerospace field.

[0004] The introduction of imidazole on heteroaramid enhances the interfacial properties, but its strong polarity increases water absorption, affecting the insulation properties. When the heteroaramid film is in a hot and humid environment, the ions produced by water dissociation increase the conductivity but greatly reduce the dielectric strength. In addition, in an electric field, gas-solid interface defects promote charge accumulation. Therefore, highly hydrophobic heteroaramid insulating materials are crucial to the development of heteroaramid in the insulation field. Considering the diverse applications of electronic devices, improving the hydrophobicity and insulation of heteroaramid films is an urgent problem to ensure their long-term operation. Summary of the invention

[0005] In view of the problems of poor hydrophobicity and poor insulation of heterocyclic aramid films in the prior art, the present invention provides a hydrophobically modified heterocyclic aramid-based insulating film, a preparation method and application thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a hydrophobically modified heterocyclic aramid-based insulating film, comprising:

[0008] Using N,N-dimethylacetamide and lithium chloride, a dissolving system is prepared;

[0009] Adding 2-(4-aminophenyl)-5-aminobenzimidazole, 1,4-phenylenediamine and terephthaloyl chloride into the dissolving system to react and obtain a heterocyclic aramid solution;

[0010] Adding alkaline substances and brominated long-chain alkanes to the heterocyclic aramid solution, heating, and reacting to obtain a modified heterocyclic aramid solution;

[0011] The modified heterocyclic aramid solution is coated, immersed in water, and dried to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0012] Furthermore, in the dissolution system, the mass ratio of N,N-dimethylacetamide to lithium chloride is (350-700):(12-24).

[0013] Furthermore, in the heterocyclic aramid solution, the mass ratio of N,N-dimethylacetamide, lithium chloride and heterocyclic aramid is (350-700):(12-24):7, and the solid content of heterocyclic aramid in the heterocyclic aramid solution is 1.0-2.0wt%.

[0014] Furthermore, the alkaline substance is sodium hydroxide, K 2 CO 3 and one or more of potassium tert-butoxide.

[0015] Furthermore, the brominated long-chain alkane is brominated hexadecane, brominated octadecane, brominated eicosane, brominated docosane or brominated tetracosane.

[0016] Furthermore, the molar ratio of the brominated long-chain alkane to 2-(4-aminophenyl)-5-aminobenzimidazole is 1:1.

[0017] Furthermore, the alkaline substance is added to the heterocyclic aramid solution, and the brominated long-chain alkane is added, and the heating temperature of the solution to obtain the modified heterocyclic aramid solution by reaction is 80° C. to 90° C.

[0018] Furthermore, the modified heterocyclic aramid solution is coated and immersed in water for 1 to 2 hours.

[0019] The present invention also provides a hydrophobically modified heterocyclic aramid-based insulating film, which is prepared by the above method.

[0020] The hydrophobically modified heterocyclic aramid-based insulating film mentioned above is used as an insulating material in the field of electrical insulation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention discloses a method for preparing a hydrophobically modified heterocyclic aramid-based insulating film. The method prepares a heterocyclic aramid polymer with high breakdown strength and high heat resistance as a substrate, and uses the active sites on the imidazole of the heterocyclic aramid to graft a hydrophobic long-chain alkane, thereby giving the heterocyclic aramid its own flame retardancy, heat resistance, excellent mechanical strength and high breakdown strength. Hydrophobic properties are given to the heterocyclic aramid, and a high-strength, high-modulus, heat-resistant, and hydrophobic heterocyclic aramid-based insulating film is successfully prepared. By modifying the active sites on the imidazole, the water absorption is reduced, and the surface is hydrophobic, so as to solve the problem of high water absorption caused by the strong polarity of the imidazole, which affects the insulation. That is, through the action of the imidazole in the film, supplemented by the surface hydrophobic function, the insulating properties of the film are doubly enhanced. The method is simple and has important significance for the application of heterocyclic aramid insulating materials in complex scenarios.

[0023] The present invention provides a hydrophobically modified heterocyclic aramid-based insulating film, which is prepared by the above method. The film has excellent hydrophobic properties, self-flaming retardancy, temperature resistance, mechanical strength and high breakdown strength, so that it can still maintain a stable insulating effect and excellent insulating properties in harsh environments such as high humidity and high voltage, which is of great significance for promoting the application of heterocyclic aramid insulating materials in complex scenarios.

[0024] As mentioned above, the hydrophobically modified heterocyclic aramid-based insulating film is used as an insulating material in the field of electrical insulation. The application of the hydrophobically modified heterocyclic aramid-based insulating film in the insulating components of electrical equipment can significantly improve the reliability and safety of the equipment. On the one hand, its excellent insulation performance can effectively prevent the occurrence of current leakage and short-circuit accidents; on the other hand, its good heat resistance and chemical corrosion resistance can ensure the long-term stable operation of the equipment in harsh environments, reduce equipment failures and safety accidents caused by aging and damage of insulating materials, and have significant application advantages and development prospects in the field of electrical insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a method for preparing a hydrophobically modified heterocyclic aramid-based insulating film of the present invention.

[0026] Figure 2 The present invention is a schematic diagram of a process flow of a method for preparing a hydrophobically modified heterocyclic aramid-based insulating film.

[0027] Figure 3 is a Weibull distribution diagram of the breakdown strength of the hydrophobically modified heterocyclic aramid insulating film in Examples 7-12 of the present invention;

[0028] Figure 4 is the breakdown strength of the hydrophobically modified heterocyclic aramid insulating film in Examples 7-12 of the present invention;

[0029] Figure 5is a thermogravimetric diagram of the hydrophobically modified heterocyclic aramid insulating film in Examples 7-12 of the present invention;

[0030] Figure 6 is a stress-strain curve diagram of the hydrophobically modified heterocyclic aramid insulating film in Examples 7-12 of the present invention;

[0031] Figure 7 The contact angle photos of the hydrophobically modified heterocyclic aramid insulating film before and after modification in Examples 7-12 of the present invention are DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0033] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0034] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0035] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0036] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0039] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0040] See also Figure 1 The present invention discloses a method for preparing a hydrophobically modified heterocyclic aramid-based insulating film, referring to Figure 1 ,include:

[0041] S1: using N, N-dimethylacetamide (DMAc) and lithium chloride to prepare a dissolving system, wherein the mass ratio of N, N-dimethylacetamide to lithium chloride in the dissolving system is (350-700):(12-24);

[0042] S2: Add 2-(4-aminophenyl)-5-aminobenzimidazole (APBZ), 1,4-phenylenediamine (PPD) and terephthaloyl chloride (TPC) to the dissolving system to react and obtain a heterocyclic aramid solution; in the heterocyclic aramid solution, the mass ratio of N,N-dimethylacetamide, lithium chloride and heterocyclic aramid is (350-700):(12-24):7, and the solid content of heterocyclic aramid in the heterocyclic aramid solution is 1.0-2.0wt% , the molar ratio of 2-(4-aminophenyl)-5-aminobenzimidazole, 1,4-phenylenediamine and terephthaloyl chloride in the heterocyclic aramid solution is (9-4):(1-6):10, and the method is: adding 2-(4-aminophenyl)-5-aminobenzimidazole and 1,4-phenylenediamine to the dissolving system, and then mechanically stirring to dissolve them in an ice-water bath at 0°C, adding terephthaloyl chloride, removing the ice-water bath, and reacting for more than 1 hour to obtain the heterocyclic aramid solution;

[0043] S3: adding alkaline substances and brominated long-chain alkanes to the heterocyclic aramid solution, heating, and reacting to obtain a modified heterocyclic aramid solution; the alkaline substances are sodium hydroxide, K 2 CO 3 and potassium tert-butoxide, the amount of the alkaline substance is 1% to 3% of the total mass of the heterocyclic aramid solution; the brominated long-chain alkane is brominated hexadecane, brominated octadecane, brominated eicosane, brominated docosane or brominated tetracosane; the molar ratio of the brominated long-chain alkane to 2-(4-aminophenyl)-5-aminobenzimidazole is 1:1, and the heating condition is 80°C to 90°C.

[0044] S4: coating the modified heterocyclic aramid solution, immersing in water for 1 to 2 hours, and drying to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0045] Example 1

[0046] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, in an ice-water bath at 0°C, the system is mechanically stirred to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 9:1:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 700:24:7, and the solid content of the obtained heterocyclic aramid is 1.0wt%; sodium hydroxide of 1% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the sodium hydroxide is dissolved, hexadecane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred for 2 hours in an 80°C water bath. The obtained solution is coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0047] Example 2

[0048] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed under the condition of an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 8:2:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 700:24:7, and the solid content of the obtained heterocyclic aramid was 1.0wt%; sodium hydroxide accounting for 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the sodium hydroxide was dissolved, hexadecane bromide in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours under the condition of an 80°C water bath. The obtained solution was coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0049] Example 3

[0050] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 7:3:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 700:24:7, and the solid content of the obtained heterocyclic aramid was 1.0wt%; sodium hydroxide accounting for 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the sodium hydroxide was dissolved, hexadecane bromide in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 80°C water bath. The obtained solution was coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0051] Example 4

[0052] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. Then, the system was mechanically stirred in an ice-water bath at 0°C to dissolve the system. TPC was added, the ice-water bath was removed, and the system was reacted for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 6:4:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 700:24:7, and the solid content of the obtained heterocyclic aramid was 1.0wt%. Sodium hydroxide accounting for 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the system was heated and stirred. After the sodium hydroxide was dissolved, hexadecane bromide having a molar ratio of 1:1 to APBZ was added, and the system was stirred for 2 hours in an 80°C water bath. The obtained solution was coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0053] Example 5

[0054] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. Then, the system was mechanically stirred in an ice-water bath at 0°C to dissolve the system. TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 5:5:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 700:24:7, and the solid content of the obtained heterocyclic aramid was 1.0wt%; sodium hydroxide accounting for 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the system was heated and stirred. After the sodium hydroxide was dissolved, hexadecane bromide in a molar ratio of 1:1 to APBZ was added, and the system was stirred for 2 hours in an 80°C water bath. The obtained solution was coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0055] Example 6

[0056] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 4:6:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 700:24:7, and the solid content of the obtained heterocyclic aramid was 1.0wt%; sodium hydroxide accounting for 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the sodium hydroxide was dissolved, hexadecane bromide in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 80°C water bath. The obtained solution was coated, immersed in water for 1 hour, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0057] Example 7

[0058] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 9:1:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0059] Example 8

[0060] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 8:2:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0061] Example 9

[0062] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 7:3:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0063] Example 10

[0064] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 6:4:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0065] Embodiment 11

[0066] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 5:5:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0067] Example 12

[0068] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring to dissolve the solution in an ice-water bath at 0°C, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 4:6:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 580:20:7, and the solid content of the obtained heterocyclic aramid was 1.2wt%; potassium tert-butoxide of 1% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, octadecane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours in an 83°C water bath. The obtained solution was coated, immersed in water for 1.2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0069] Example 13

[0070] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 9:1:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0071] Embodiment 14

[0072] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 8:2:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0073] Embodiment 15

[0074] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 7:3:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0075] Example 16

[0076] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 6:4:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0077] Embodiment 17

[0078] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 5:5:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0079] Embodiment 18

[0080] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 4:6:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 466:16.3:7, and the solid content of the obtained heterocyclic aramid was 1.5wt%; potassium carbonate accounting for 2% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium carbonate was dissolved, bromoeicosane in a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 85°C water bath. The obtained solution was coated, immersed in water for 1.5 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0081] Embodiment 19

[0082] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 9:1:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of 1:1 with APBZ was added, and the solution was stirred for 2 hours in an 88°C water bath. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0083] Embodiment 20

[0084] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 8:2:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 88°C water bath. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0085] Embodiment 21

[0086] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring to dissolve the solution in an ice-water bath at 0°C, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 7:3:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 88°C water bath. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0087] Embodiment 22

[0088] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 6:4:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 88°C water bath. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0089] Embodiment 23

[0090] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 5:5:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in an 88°C water bath. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0091] Embodiment 24

[0092] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed in an ice-water bath at 0°C to dissolve the solution, TPC was added, the ice-water bath was removed, and the reaction was performed for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 4:6:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 400:14:7, and the solid content of the obtained heterocyclic aramid was 1.75wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, bromodioxane of a molar ratio of 1:1 to APBZ was added, and the solution was stirred for 2 hours in a water bath at 90°C. The obtained solution was coated, immersed in water for 1.75 hours, and dried at 105°C for 30 minutes after exchanging with water to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0093] Embodiment 25

[0094] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, the system is mechanically stirred in an ice-water bath at 0°C to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 9:1:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 350:12:7, and the solid content of the obtained heterocyclic aramid is 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the potassium tert-butoxide is dissolved, tetracosane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred in a water bath at 90°C for 2 hours. The obtained solution is coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0095] Embodiment 26

[0096] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, the system is mechanically stirred in an ice-water bath at 0°C to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 8:2:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 350:12:7, and the solid content of the obtained heterocyclic aramid is 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the potassium tert-butoxide is dissolved, tetracosane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred for 2 hours in a water bath at 90°C. The obtained solution is coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0097] Embodiment 27

[0098] A dissolving system was prepared, and APBZ and PPD were added to the dissolving system. After mechanical stirring was performed under the condition of an ice-water bath at 0°C to dissolve the APBZ and PPD, TPC was added, the ice-water bath was removed, and the reaction was carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC was 7:3:10, the mass ratio of DMAc, LiCl and heterocyclic aramid was 350:12:7, and the solid content of the obtained heterocyclic aramid was 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system was added to the heterocyclic aramid solution to provide an alkaline environment, and the solution was heated and stirred. After the potassium tert-butoxide was dissolved, tetracosane bromide was added in a molar ratio of 1:1 to APBZ, and the solution was stirred for 2 hours under the condition of a water bath at 90°C. The obtained solution was coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0099] Embodiment 28

[0100] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, the system is mechanically stirred in an ice-water bath at 0°C to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 6:4:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 350:12:7, and the solid content of the obtained heterocyclic aramid is 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the potassium tert-butoxide is dissolved, tetracosane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred in a water bath at 90°C for 2 hours. The obtained solution is coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0101] Embodiment 29

[0102] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, the system is mechanically stirred in an ice-water bath at 0°C to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 5:5:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 350:12:7, and the solid content of the obtained heterocyclic aramid is 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the potassium tert-butoxide is dissolved, tetracosane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred in a water bath at 90°C for 2 hours. The obtained solution is coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0103] Embodiment 30

[0104] A dissolving system is prepared, and APBZ and PPD are added to the dissolving system. Then, the system is mechanically stirred in an ice-water bath at 0°C to dissolve the system, and then TPC is added. The ice-water bath is removed, and the reaction is carried out for more than 1 hour to obtain a heterocyclic aramid solution, wherein the molar ratio of APBZ, PPD and TPC is 4:6:10, the mass ratio of DMAc, LiCl and heterocyclic aramid is 350:12:7, and the solid content of the obtained heterocyclic aramid is 2.0wt%; potassium tert-butoxide of 3% of the total mass of the system is added to the heterocyclic aramid solution to provide an alkaline environment, and the system is heated and stirred. After the potassium tert-butoxide is dissolved, tetracosane bromide is added in a molar ratio of 1:1 to APBZ, and the system is stirred in a water bath at 90°C for 2 hours. The obtained solution is coated, immersed in water for 2 hours, exchanged with water, and then dried at 105°C for 30 minutes to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

[0105] Taking implementation cases 7-12 as an example, the performance of the hydrophobic insulating film obtained by the present invention is tested, see Figure 3 and Figure 4 It should be noted that: according to the dosage ratio of APBZ to TPC in Examples 7-12, when the dosage of TPC changes, the hydrophobically modified heterocyclic aramid-based insulating films prepared in Examples 7-12 are recorded as: Ax / Py, where x / y = APBZ mass / APBZ mass. The insulating films prepared in Examples 7-12 were tested for breakdown strength. The experimental results show that the hydrophobically modified heterocyclic aramid-based insulating films have a high breakdown strength in air, up to 88.13 kV / mm. It is particularly noted that when the content of 2-(4-aminophenyl)-5-aminobenzimidazole in the insulating film increases, its breakdown strength basically shows an upward trend. See Figure 5 The hydrophobic insulating films prepared in Examples 7-12 were subjected to thermogravimetric analysis. The hydrophobic insulating films began to experience significant mass loss at 550°C, indicating that the hydrophobic insulating films have high heat resistance. Figure 6 The hydrophobic insulating films prepared in Examples 7-12 were subjected to tensile tests. The results showed that the tensile strength of the hydrophobic insulating films was basically maintained above 100 MPa, and could reach up to 160 MPa, indicating that the films had excellent mechanical properties, which was beneficial to the subsequent insulation applications of the films. Figure 7 , the contact angle test of the hydrophobic insulating film prepared in Examples 7-12 was conducted, and it was found that the contact angle of the film was increased from 75.4° before modification to 104.0°, and the hydrophobic performance of the hydrophobic insulating film was greatly improved. The improvement of the hydrophobic performance can prevent the film from being broken down due to wet water, which is of great significance for the subsequent complex insulation applications of the film. It can be seen that the present invention prepares HA in multiple proportions from bottom to top by adjusting the content of the third monomer, namely APBZ, and improves the strong water absorption of imidazole by grafting long-chain alkanes, so as to prepare a hydrophobically modified heterocyclic aramid insulating film. It is worth noting that the film preparation process is completely water-free, and the solution has the characteristics of water-sensitive processing. By using this characteristic, we prepare heterocyclic aramid insulating film, which has the characteristics of high strength, high modulus and hydrophobicity while improving the insulation performance. In terms of preparation technology, it has the characteristics of short preparation process, simple preparation process, and no dependence on equipment conditions, and the prepared insulating material can be directly put into use, which is conducive to large-scale preparation.

[0106] The present invention provides a hydrophobically modified heterocyclic aramid-based insulating film, which is prepared by the above method. The film has excellent hydrophobicity, self-flaming retardancy, temperature resistance, mechanical strength and high breakdown strength, etc., so that it can still maintain a stable insulating effect and excellent insulating performance in harsh environments such as high humidity and high voltage, which is of great significance for promoting the application of heterocyclic aramid insulating materials in complex scenarios.

[0107] For example, the above-mentioned hydrophobically modified heterocyclic aramid-based insulating film is used as an insulating material in the field of electrical insulation. The application of the hydrophobically modified heterocyclic aramid-based insulating film in the insulating components of electrical equipment can significantly improve the reliability and safety of the equipment. On the one hand, its excellent insulation performance can effectively prevent the occurrence of current leakage and short-circuit accidents; on the other hand, its good heat resistance and chemical corrosion resistance can ensure the long-term stable operation of the equipment in harsh environments, reduce equipment failures and safety accidents caused by aging and damage of insulating materials, and have significant application advantages and development prospects in the field of electrical insulation.

[0108] In summary, the present invention provides a hydrophobically modified heterocyclic aramid-based insulating film, a preparation method and an application thereof. The method prepares a heterocyclic aramid polymer with high breakdown strength and high heat resistance as a substrate, and uses the active sites on the imidazole of the heterocyclic aramid to graft hydrophobic long-chain alkanes, thereby giving the heterocyclic aramid its own flame retardancy, heat resistance, excellent mechanical strength and high breakdown strength. Hydrophobic properties are given to the heterocyclic aramid-based insulating film, and a high-strength, high-modulus, heat-resistant, and hydrophobic heterocyclic aramid-based insulating film is successfully prepared. Through the action of imidazole in the film, supplemented by the surface hydrophobic function, the insulating properties of the film are doubly enhanced. The method is simple and has important significance for the application of heterocyclic aramid insulating materials in complex scenarios.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A method for preparing a hydrophobically modified heterocyclic aramid-based insulating film, characterized in that: include: Using N,N-dimethylacetamide and lithium chloride, a dissolving system is prepared; Adding 2-(4-aminophenyl)-5-aminobenzimidazole, 1,4-phenylenediamine and terephthaloyl chloride into the dissolving system to react and obtain a heterocyclic aramid solution; Adding alkaline substances and brominated long-chain alkanes to the heterocyclic aramid solution, heating, and reacting to obtain a modified heterocyclic aramid solution; The modified heterocyclic aramid solution is coated, immersed in water, and dried to obtain a hydrophobically modified heterocyclic aramid-based insulating film.

2. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: In the dissolution system, the mass ratio of N,N-dimethylacetamide to lithium chloride is (350-700):(12-24).

3. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: In the heterocyclic aramid solution, the mass ratio of N,N-dimethylacetamide, lithium chloride and heterocyclic aramid is (350-700):(12-24):7, and the solid content of heterocyclic aramid in the heterocyclic aramid solution is 1.0-2.0wt%.

4. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: The alkaline substance is one or more of sodium hydroxide, K2CO3 and potassium tert-butoxide.

5. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: The brominated long-chain alkane is brominated hexadecane, brominated octadecane, brominated eicosane, brominated docosane or brominated tetracosane.

6. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: The molar ratio of the brominated long-chain alkane to 2-(4-aminophenyl)-5-aminobenzimidazole is 1:

1.

7. The method for preparing a hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: The alkaline substance is added to the heterocyclic aramid solution, and the brominated long-chain alkane is added, and the solution is heated to obtain the modified heterocyclic aramid solution. The heating temperature is 80° C. to 90° C.

8. The method for preparing the hydrophobically modified heterocyclic aramid-based insulating film according to claim 1, characterized in that: The modified heterocyclic aramid solution is coated and immersed in water for 1 to 2 hours.

9. A hydrophobically modified heterocyclic aramid-based insulating film, characterized in that: Prepared by the method described in any one of claims 1 to 8.

10. Use of the hydrophobically modified heterocyclic aramid-based insulating film as claimed in claim 9 as an insulating material in the field of electrical insulation.

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