An aviation cable based on polyimide film

Abstract

The application discloses an aviation cable based on a polyimide film and belongs to the technical field of cables. The aviation cable comprises a cable core, a braided layer and a sheath layer which are sequentially arranged from inside to outside. The cable core is composed of a plurality of wire cores. The wire core comprises a conductor, an insulating layer and a modified polyimide film from inside to outside. The conductor is composed of a tinned copper metal monofilament, and the insulating layer is made of polytetrafluoroethylene. The braided layer is made of a silver-plated copper flat strip. The sheath layer is made of cross-linked ethylene-tetrafluoroethylene. The boron nitride nanosheet is surface-modified by a special modifier, and is introduced into a polyimide matrix, so that the performance of the obtained film is comprehensively improved.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, and specifically relates to an aviation cable based on polyimide film. Background Technology

[0002] Polyimide film has broad application prospects in high-end cable fields such as aviation and aerospace due to its excellent high and low temperature resistance, electrical insulation properties, and mechanical properties. As a key component of the neural network of aircraft, the performance of aviation cables is directly related to the safety and reliability of the entire aircraft. Therefore, they need to be lightweight, high temperature resistant, flame retardant, highly reliable, and have excellent mechanical strength and environmental resistance.

[0003] Currently, polyimide film is used as insulation or sheathing material in aviation cables. However, traditional polyimide materials still have some shortcomings that limit their application in more demanding aviation environments. First, pure polyimide film generally has poor thermal conductivity, which is not conducive to the timely dissipation of heat generated when the cable is energized, potentially leading to localized overheating and affecting the cable's long-term service life and safety. Second, although polyimide itself has a certain degree of flame retardancy, its limiting oxygen index (LOI) still has room for improvement. To meet the extremely high fire safety requirements of the aviation field, its flame retardant performance needs to be further enhanced. Furthermore, under long-term mechanical stress, thermal stress, and potential radiation environments, the mechanical strength and durability of polyimide film may decrease, making it difficult to fully meet the requirements of long-life, high-reliability aviation applications.

[0004] To improve the performance of polyimide, existing technologies have attempted to add various inorganic fillers, such as boron nitride (BN) and alumina, to its matrix to enhance its thermal conductivity and flame retardant properties. However, untreated nanofillers tend to agglomerate in the polymer matrix, making uniform dispersion difficult. This not only fails to effectively construct a thermally conductive network but may also introduce defects, leading to a deterioration in the material's mechanical and insulation properties. Therefore, developing a modification technique that enables highly uniform dispersion of fillers in the polyimide matrix and the formation of a strong interfacial bond is crucial for preparing high-performance aerospace cables.

[0005] Therefore, in order to solve the above problems, the present invention provides an aviation cable based on polyimide film. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an aviation cable based on polyimide film.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] An aviation cable based on polyimide film includes a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0009] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene.

[0010] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0011] In a more optimized manner, the preparation process of the modified polyimide film is as follows:

[0012] Step 1: Under a protective atmosphere, 4,4'-diaminodiphenyl ether was added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; modified boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed; the resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly; 4,4'-(hexafluoroisopropene)phthalic anhydride was slowly added at 0-5℃ and stirred continuously for 24 h to obtain a polyamic acid mixed solution;

[0013] Step 2: Cast the polyamic acid mixture onto a glass substrate to form a film, and carry out a thermal imidization reaction under a protective atmosphere to obtain a modified polyimide film.

[0014] In a more optimized manner, the raw materials for preparing the polyamic acid mixed solution include the following components: by weight, 20-30 parts of 4,4'-diaminodiphenyl ether, 2-3 parts of modified boron nitride nanosheets, and 40-50 parts of 4,4'-(hexafluoroisopropene)phthalic anhydride.

[0015] More optimally, the parameters of the thermal imidization reaction are: 80℃ / 3h, 100℃ / 1h, 200℃ / 1h, and 300℃ / 1h.

[0016] In a more optimized manner, the preparation process of the modified boron nitride nanosheets is as follows:

[0017] A1: Under nitrogen protection, magnesium, iodine, and anhydrous tetrahydrofuran were mixed and stirred until homogeneous. A solution of anhydrous tetrahydrofuran containing 2-methyl-5-bromobenzimidazole was slowly added. The temperature was raised to 80-90℃ and refluxed for 1-2 hours. After cooling, the product was added dropwise to a solution of anhydrous tetrahydrofuran containing cyanuric chloride and stirred at 40-50℃ for 1-2 hours. After the reaction was completed, post-processing was performed to obtain intermediate 1.

[0018] A2: Under nitrogen protection, intermediate 1 and anhydrous aluminum chloride were added to anhydrous o-dichlorobenzene and stirred at room temperature for 30-40 min. Then resorcinol was slowly added, the temperature was raised to 80-90℃, and the reaction was stirred for 1-2 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was slowly added, and the solvent was removed by vacuum distillation. The obtained solid was washed and dried to obtain intermediate 2.

[0019] A3: Mix intermediate 2, acetone, and potassium carbonate, and stir at 40-50℃ for 30-40 min. Then slowly add an acetone solution of 2-bromopropionic acid (6-methylheptyl) ester. After the addition is complete, raise the temperature to 70-80℃ and reflux for 6-7 h. After the reaction is complete, cool to room temperature, remove acetone by vacuum distillation, and then perform post-treatment to obtain the modifier.

[0020] A4: Boron nitride nanosheets were ultrasonically dispersed in N,N-dimethylformamide, a modifier was added, and the mixture was stirred at room temperature for 18-20 hours. The mixture was then filtered, washed, and dried to obtain modified boron nitride nanosheets.

[0021] In this scheme, firstly, a Grignard reagent is formed by reacting 2-methyl-5-bromobenzimidazole with magnesium scrap under iodine catalysis, which then reacts with cyanuric chloride to generate intermediate 1 with a triazine ring core. Subsequently, under Lewis acid anhydrous aluminum chloride catalysis, intermediate 1 undergoes an alkylation reaction with resorcinol to construct intermediate 2 with a larger planar conjugated structure. Afterward, the phenolic hydroxyl group of intermediate 2 undergoes an etherification reaction with 2-bromopropionic acid (6-methylheptyl) ester in the presence of potassium carbonate, grafting a long-chain alkyl ester onto it, ultimately yielding the target modifier. The extended planar conjugated system in the modifier's molecular structure allows it to be physically adsorbed onto the surface of boron nitride nanosheets through a strong π-π conjugation effect, while the introduced long-chain alkyl group effectively improves the compatibility and dispersion stability of boron nitride nanosheets in the organic polymer matrix, thus achieving efficient and stable surface modification.

[0022] The structure of the modifier is shown below:

[0023]

[0024] In a more optimized manner, the raw materials for preparing intermediate 1 include the following components: by weight, 4-5 parts magnesium, 1-2 parts iodine, 42-43 parts 2-methyl-5-bromobenzimidazole, and 18-20 parts cyanuric chloride.

[0025] In a more optimized manner, the raw materials for preparing intermediate 2 include the following components: by weight, 40-45 parts of intermediate 1, 2-3 parts of anhydrous aluminum chloride, and 11-12 parts of resorcinol.

[0026] In a more optimized manner, the raw materials for preparing the modifier include the following components: by weight, 50-55 parts of intermediate 2, 16-18 parts of potassium carbonate, and 25-30 parts of 2-bromopropionic acid (6-methylheptyl) ester.

[0027] In a more optimized manner, the raw materials for preparing the modified boron nitride nanosheets include the following components: 10-12 parts by weight of boron nitride nanosheets and 2-3 parts by weight of modifier.

[0028] The beneficial effects of this invention are:

[0029] This invention utilizes a specialized modifier to surface-modify boron nitride nanosheets and introduces them into a polyimide matrix, resulting in a comprehensive improvement in the performance of the resulting film. The modifier, through its planar conjugated structure, generates strong π-π adsorption with the boron nitride nanosheets. While fully preserving the intrinsic structure of the nanosheets, the long-chain alkyl groups at the ends achieve uniform and stable dispersion within the polyimide matrix, constructing a highly efficient thermal conductivity network and significantly enhancing thermal conductivity. Regarding flame retardancy, the triazine and benzimidazole rings in the modifier molecule play a crucial role. These nitrogen-rich heterocycles catalyze the formation of a dense char layer and release inert gases at high temperatures, achieving highly efficient fire resistance through the synergistic effect of gas-phase and condensed-phase flame retardancy. Simultaneously, the strong interfacial bonding based on π-π adsorption and the compatibilizing effect of the long-chain alkyl groups effectively transfers stress from the polymer matrix to the high-modulus nanosheets, thereby significantly enhancing the mechanical strength and durability of the film. This multi-layered synergistic effect enables the composite material to perfectly meet the stringent requirements of aerospace cables. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: An aviation cable based on polyimide film, comprising a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0032] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene.

[0033] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0034] The preparation process of the modified polyimide film is as follows:

[0035] Step 1: Under a protective atmosphere, 20 parts of 4,4'-diaminodiphenyl ether were added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; 2 parts of modified boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed; the resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly; 40 parts of 4,4'-(hexafluoroisopropene)phthalic anhydride were slowly added at 0℃ and stirred continuously for 24 h to obtain a polyamic acid mixed solution;

[0036] Step 2: Cast the polyamic acid mixture solution onto a glass substrate to form a film, and carry out a thermal imidization reaction (80℃ / 3h, 100℃ / 1h, 200℃ / 1h and 300℃ / 1h) under a protective atmosphere to obtain a modified polyimide film;

[0037] The preparation process of the modified boron nitride nanosheets is as follows:

[0038] A1: Under nitrogen protection, 4 parts magnesium, 1 part iodine, and anhydrous tetrahydrofuran were mixed and stirred evenly. The anhydrous tetrahydrofuran solution of 2-methyl-5-bromobenzimidazole (42 parts 2-methyl-5-bromobenzimidazole) was slowly added. The temperature was raised to 80°C and refluxed for 1 hour. After cooling, the obtained product was added dropwise to anhydrous tetrahydrofuran solution of cyanuric chloride (18 parts cyanuric chloride). The mixture was stirred at 40°C for 1 hour. After the reaction was completed, the product was post-processed to obtain intermediate 1.

[0039] A2: Under nitrogen protection, 40 parts of intermediate 1 and 2 parts of anhydrous aluminum chloride were added to anhydrous o-dichlorobenzene and stirred at room temperature for 30 min. Then, 11 parts of resorcinol were slowly added, the temperature was raised to 80℃, and the reaction was stirred for 1 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was slowly added, and the solvent was removed by vacuum distillation. The obtained solid was washed and dried to obtain intermediate 2.

[0040] A3: Mix 50 parts of intermediate 2, acetone, and 16 parts of potassium carbonate, stir at 40°C for 30 min, then slowly add dropwise an acetone solution of 2-bromopropionic acid (6-methylheptyl) ester (25 parts of 2-bromopropionic acid (6-methylheptyl) ester). After the addition is complete, raise the temperature to 70°C and reflux for 6 h. After the reaction is complete, cool to room temperature, remove acetone by vacuum distillation, and then perform post-processing to obtain the modifier.

[0041] A4: 10 parts of boron nitride nanosheets were ultrasonically dispersed in N,N-dimethylformamide, 2 parts of modifier were added, and the mixture was stirred at room temperature for 18 hours. After filtration, washing, and drying, modified boron nitride nanosheets were obtained.

[0042] Example 2: An aviation cable based on polyimide film, comprising a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0043] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene.

[0044] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0045] The preparation process of the modified polyimide film is as follows:

[0046] Step 1: Under a protective atmosphere, 30 parts of 4,4'-diaminodiphenyl ether were added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; 3 parts of modified boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed; the resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly; 50 parts of 4,4'-(hexafluoroisopropene)phthalic anhydride were slowly added at 0℃ and stirred continuously for 24 h to obtain a polyamic acid mixed solution;

[0047] Step 2: Cast the polyamic acid mixture solution onto a glass substrate to form a film, and carry out a thermal imidization reaction (80℃ / 3h, 100℃ / 1h, 200℃ / 1h and 300℃ / 1h) under a protective atmosphere to obtain a modified polyimide film;

[0048] The preparation process of the modified boron nitride nanosheets is as follows:

[0049] A1: Under nitrogen protection, 5 parts magnesium, 2 parts iodine, and anhydrous tetrahydrofuran were mixed and stirred evenly. The anhydrous tetrahydrofuran solution of 2-methyl-5-bromobenzimidazole (43 parts 2-methyl-5-bromobenzimidazole) was slowly added. The temperature was raised to 90°C and refluxed for 2 hours. After cooling, the obtained product was added dropwise to anhydrous tetrahydrofuran solution of cyanuric chloride (20 parts cyanuric chloride). The mixture was stirred at 50°C for 2 hours. After the reaction was completed, the product was post-processed to obtain intermediate 1.

[0050] A2: Under nitrogen protection, 45 parts of intermediate 1 and 3 parts of anhydrous aluminum chloride were added to anhydrous o-dichlorobenzene and stirred at room temperature for 40 min. Then, 12 parts of resorcinol were slowly added, the temperature was raised to 90℃, and the reaction was stirred for 2 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was slowly added, and the solvent was removed by vacuum distillation. The obtained solid was washed and dried to obtain intermediate 2.

[0051] A3: Mix 55 parts of intermediate 2, acetone, and 18 parts of potassium carbonate, stir at 50°C for 40 min, then slowly add dropwise an acetone solution of 2-bromopropionic acid (6-methylheptyl) ester (30 parts of 2-bromopropionic acid (6-methylheptyl) ester). After the addition is complete, raise the temperature to 80°C and reflux for 7 h. After the reaction is complete, cool to room temperature, remove acetone by vacuum distillation, and then perform post-processing to obtain the modifier.

[0052] A4: 12 parts of boron nitride nanosheets were ultrasonically dispersed in N,N-dimethylformamide, 3 parts of modifier were added, and the mixture was stirred at room temperature for 20 h. After filtration, washing, and drying, modified boron nitride nanosheets were obtained.

[0053] Example 3: An aviation cable based on polyimide film, comprising a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0054] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene.

[0055] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0056] The preparation process of the modified polyimide film is as follows:

[0057] Step 1: Under a protective atmosphere, 25 parts of 4,4'-diaminodiphenyl ether were added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; 2.5 parts of modified boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed. The resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly. 45 parts of 4,4'-(hexafluoroisopropene)phthalic anhydride were slowly added at 0°C and stirred continuously for 24 hours to obtain a polyamic acid mixed solution.

[0058] Step 2: Cast the polyamic acid mixture solution onto a glass substrate to form a film, and carry out a thermal imidization reaction (80℃ / 3h, 100℃ / 1h, 200℃ / 1h and 300℃ / 1h) under a protective atmosphere to obtain a modified polyimide film;

[0059] The preparation process of the modified boron nitride nanosheets is as follows:

[0060] A1: Under nitrogen protection, 4.5 parts magnesium, 1.5 parts iodine, and anhydrous tetrahydrofuran were mixed and stirred evenly. A solution of anhydrous tetrahydrofuran containing 2-methyl-5-bromobenzimidazole (42.5 parts 2-methyl-5-bromobenzimidazole) was slowly added. The temperature was raised to 85°C and refluxed for 1.5 h. After cooling, the obtained product was added dropwise to a solution of anhydrous tetrahydrofuran containing cyanuric chloride (19 parts cyanuric chloride). The mixture was stirred at 45°C for 1.5 h. After the reaction was completed, post-processing was performed to obtain intermediate 1.

[0061] A2: Under nitrogen protection, 42.5 parts of intermediate 1 and 2.5 parts of anhydrous aluminum chloride were added to anhydrous o-dichlorobenzene and stirred at room temperature for 35 min. Then, 11.5 parts of resorcinol were slowly added, the temperature was raised to 85℃, and the reaction was stirred for 1.5 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was slowly added, and the solvent was removed by vacuum distillation. The obtained solid was washed and dried to obtain intermediate 2.

[0062] A3: Mix 52.5 parts of intermediate 2, acetone, and 17 parts of potassium carbonate, stir at 45°C for 35 min, then slowly add dropwise an acetone solution of 2-bromopropionic acid (6-methylheptyl) ester (27.5 parts of 2-bromopropionic acid (6-methylheptyl) ester). After the addition is complete, raise the temperature to 75°C and reflux for 6.5 h. After the reaction is complete, cool to room temperature, remove acetone by vacuum distillation, and then perform post-processing to obtain the modifier.

[0063] A4: 11 parts of boron nitride nanosheets were ultrasonically dispersed in N,N-dimethylformamide, 2.5 parts of modifier were added, and the mixture was stirred at room temperature for 19 h. After filtration, washing, and drying, modified boron nitride nanosheets were obtained.

[0064] Comparative Example 1: No modification was made to the boron nitride nanosheets, as follows:

[0065] An aviation cable based on polyimide film includes a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0066] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene.

[0067] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0068] The preparation process of the modified polyimide film is as follows:

[0069] Step 1: Under a protective atmosphere, 25 parts of 4,4'-diaminodiphenyl ether were added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; 2.5 parts of boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed. The resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly. 45 parts of 4,4'-(hexafluoroisopropene)phthalic anhydride were slowly added at 0°C and stirred continuously for 24 hours to obtain a polyamic acid mixed solution.

[0070] Step 2: Cast the polyamic acid mixture onto a glass substrate to form a film, and carry out a thermal imidization reaction (80℃ / 3h, 100℃ / 1h, 200℃ / 1h and 300℃ / 1h) under a protective atmosphere to obtain a modified polyimide film.

[0071] Comparative Example 2: Without the addition of boron nitride nanosheets, as follows:

[0072] An aviation cable based on polyimide film includes a cable core, a braided layer, and a sheath layer arranged sequentially from the inside out;

[0073] The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments twisted together, and the insulation layer is made of polytetrafluoroethylene.

[0074] The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

[0075] The preparation process of the polyimide film is as follows:

[0076] Step 1: Under a protective atmosphere, 25 parts of 4,4'-diaminodiphenyl ether were added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; 45 parts of 4,4'-(hexafluoroisopropene) phthalic anhydride were slowly added at 0°C and stirred continuously for 24 hours to obtain a polyamic acid mixed solution.

[0077] Step 2: Cast the polyamic acid mixture onto a glass substrate to form a film, and carry out a thermal imidization reaction (80℃ / 3h, 100℃ / 1h, 200℃ / 1h and 300℃ / 1h) under a protective atmosphere to obtain a modified polyimide film.

[0078] Test Experiment (1):

[0079] The polyimide films obtained in the examples and comparative examples were subjected to the following tests:

[0080] (1) In accordance with standard GB / T 1040-1998, tensile strength was tested using an electronic universal testing machine at a tensile rate of 50 mm / min;

[0081] (2) The thermal conductivity of the thin film was measured using a laser thermal conductivity meter;

[0082] (3) The LOI value was measured according to standard GB / T 2406-1993, and the data obtained are shown in Table 1 below;

[0083] Table 1

[0084] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Tensile strength (MPa) 162.2 159.6 162.8 145.3 112.4 <![CDATA[Thermal conductivity (W.m -1 .K -1 )]]> 1.65 1.71 1.76 0.98 0.21 LOI (%) ＞40 ＞40 ＞40 38 35

[0085] Detection Experiment (II)

[0086] The cable obtained in the example was subjected to the following tests:

[0087] The radiation environment was simulated, and a radiation resistance test was conducted. The radiation dose rate was controlled at 20 kGy / h, and the total dose was controlled at 1 mgy. The appearance, attenuation, and voltage standing wave ratio (VSWR) performance of the cable were tested after the radiation resistance test. The data obtained are shown in Table 2.

[0088] Table 2

[0089] project Example 1 Example 2 Example 3 Appearance In good condition In good condition In good condition 18GHz attenuation change rate (%) 22.4 22.5 21.5 Voltage standing wave ratio change rate (%) 2.8 2.7 2.6

[0090] Conclusion: Based on the technical solution and experimental data provided by this invention, it can be seen that the aviation cable based on polyimide film involved in this invention achieves a significant improvement in the overall performance of the cable by using modified polyimide film as the outer layer of the core and combining it with a specific core structure, braided layer and sheath layer.

[0091] Specifically, by introducing modified boron nitride nanosheets and surface-modifying them with a special modifier, the polyimide film exhibits excellent properties in terms of mechanical properties, thermal conductivity, and flame retardancy. Experimental data show that the modified polyimide films prepared in Examples 1 to 3 all have tensile strengths higher than 159 MPa and thermal conductivity reaching 1.65 W / m². -1 .K -1 The limiting oxygen index (LOI) of all samples is greater than 40%, demonstrating good mechanical strength, thermal conductivity, and flame retardant properties. Compared with Comparative Example 1 (without modified boron nitride nanosheets) and Comparative Example 2 (without added boron nitride nanosheets), the modified film of this invention has significant advantages in all aspects of performance.

[0092] Furthermore, the radiation resistance test results show that the cable prepared by the present invention remains intact after being subjected to high doses of radiation, and the rate of change in electrical performance is controlled at a low level, indicating that it has good environmental adaptability and long-term stability.

[0093] In summary, this invention provides a high-performance cable suitable for the aerospace field through optimization of material structure design and manufacturing process, and has good prospects for widespread application.

[0094] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0095] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. An aviation cable based on polyimide film, characterized in that, It includes the cable core, braided layer and sheath layer arranged sequentially from the inside out; The cable core is composed of multiple strands of wire, and each strand includes a conductor, an insulation layer, and a modified polyimide film from the inside out; wherein, the conductor is composed of tin-plated copper metal monofilaments stranded together, and the insulation layer is made of polytetrafluoroethylene. The braided layer is made of silver-plated copper flat strip; the sheath layer is made of cross-linked ethylene-tetrafluoroethylene.

2. The aviation cable based on polyimide film according to claim 1, characterized in that, The preparation process of the modified polyimide film is as follows: Step 1: Under a protective atmosphere, 4,4'-diaminodiphenyl ether was added to N,N-dimethylacetamide and stirred until completely dissolved to obtain a 4,4'-diaminodiphenyl ether solution; modified boron nitride nanosheets were added to N,N-dimethylacetamide and ultrasonically dispersed; the resulting dispersion was added to the 4,4'-diaminodiphenyl ether solution and stirred evenly; 4,4'-(hexafluoroisopropene)phthalic anhydride was slowly added at 0-5℃ and stirred continuously for 24 h to obtain a polyamic acid mixed solution; Step 2: Cast the polyamic acid mixture onto a glass substrate to form a film, and carry out a thermal imidization reaction under a protective atmosphere to obtain a modified polyimide film.

3. The aviation cable based on polyimide film according to claim 2, characterized in that, The raw materials for preparing the polyamic acid mixed solution include the following components: by weight, 20-30 parts of 4,4'-diaminodiphenyl ether, 2-3 parts of modified boron nitride nanosheets, and 40-50 parts of 4,4'-(hexafluoroisopropene) phthalic anhydride.

4. The aviation cable based on polyimide film according to claim 2, characterized in that, The parameters for the thermal imidization reaction are: 80℃ / 3h, 100℃ / 1h, 200℃ / 1h, and 300℃ / 1h.

5. An aviation cable based on polyimide film according to claim 2, characterized in that, The preparation process of the modified boron nitride nanosheets is as follows: A1: Under nitrogen protection, magnesium, iodine, and anhydrous tetrahydrofuran were mixed and stirred until homogeneous. A solution of anhydrous tetrahydrofuran containing 2-methyl-5-bromobenzimidazole was slowly added. The temperature was raised to 80-90℃ and refluxed for 1-2 hours. After cooling, the product was added dropwise to a solution of anhydrous tetrahydrofuran containing cyanuric chloride and stirred at 40-50℃ for 1-2 hours. After the reaction was completed, post-processing was performed to obtain intermediate 1. A2: Under nitrogen protection, intermediate 1 and anhydrous aluminum chloride were added to anhydrous o-dichlorobenzene and stirred at room temperature for 30-40 min. Then resorcinol was slowly added, the temperature was raised to 80-90℃, and the reaction was stirred for 1-2 h. After the reaction was completed, the mixture was cooled to room temperature, ice water was slowly added, and the solvent was removed by vacuum distillation. The obtained solid was washed and dried to obtain intermediate 2. A3: Mix intermediate 2, acetone, and potassium carbonate, and stir at 40-50℃ for 30-40 min. Then slowly add an acetone solution of 2-bromopropionic acid (6-methylheptyl) ester. After the addition is complete, raise the temperature to 70-80℃ and reflux for 6-7 h. After the reaction is complete, cool to room temperature, remove acetone by vacuum distillation, and then perform post-treatment to obtain the modifier. A4: Boron nitride nanosheets were ultrasonically dispersed in N,N-dimethylformamide, a modifier was added, and the mixture was stirred at room temperature for 18-20 hours. The mixture was then filtered, washed, and dried to obtain modified boron nitride nanosheets.

6. An aviation cable based on polyimide film according to claim 5, characterized in that, The raw materials for preparing intermediate 1 include the following components: by weight, 4-5 parts magnesium, 1-2 parts iodine, 42-43 parts 2-methyl-5-bromobenzimidazole, and 18-20 parts cyanuric chloride.

7. An aviation cable based on polyimide film according to claim 5, characterized in that, The raw materials for preparing intermediate 2 include the following components: by weight, 40-45 parts of intermediate 1, 2-3 parts of anhydrous aluminum chloride, and 11-12 parts of resorcinol.

8. An aviation cable based on polyimide film according to claim 5, characterized in that, The raw materials for preparing the modifier include the following components: by weight, 50-55 parts of intermediate 2, 16-18 parts of potassium carbonate, and 25-30 parts of 2-bromopropionic acid (6-methylheptyl) ester.

9. An aviation cable based on polyimide film according to claim 5, characterized in that, The raw materials for preparing the modified boron nitride nanosheets include the following components: by weight, 10-12 parts boron nitride nanosheets and 2-3 parts modifier.

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