Cable insulation layer material based on PTFE film and preparation method thereof

Abstract

The invention discloses a cable insulation layer material based on a PTFE film and a preparation method thereof, and relates to the technical field of cable insulation layer materials, the preparation method of the cable insulation layer material based on the PTFE film comprises the following steps: adding water glass modified carbon nanotubes into a bio-based compatilizer, heating to 70-75 DEG C, and stirring for 30-45 min to obtain an insulation filler; adding the fluorine-containing ionic liquid into polytetrafluoroethylene, uniformly stirring, adding the ethylene-propylene copolymer, uniformly stirring, adding the insulating filler, and uniformly stirring to obtain a polytetrafluoroethylene mixture; and coating the polytetrafluoroethylene mixture on a substrate in a casting manner, forming a film, drying, sintering, molding, stripping and rolling to obtain the cable insulation layer material based on the PTFE film.

Description

Technical Field

[0001] This invention relates to the field of cable insulation material technology, specifically a PTFE film-based cable insulation material and its preparation method. Background Technology

[0002] In the field of cable insulation materials, polytetrafluoroethylene (PTFE) is an ideal substrate due to its excellent resistance to high and low temperatures, chemical stability, and electrical insulation properties. However, in practical applications, various insulating fillers (such as carbon nanotubes, inorganic nanoparticles, etc.) are often added to the PTFE matrix to further improve its mechanical properties, thermal conductivity, or insulation properties.

[0003] However, PTFE has a highly symmetrical molecular chain structure and extremely low polarity, while most insulating fillers often have certain polarity or functional groups on their surface, resulting in poor compatibility between the two. Furthermore, the insulating fillers themselves, due to their high surface energy, are prone to agglomeration, making it difficult to achieve uniform dispersion within the PTFE matrix. This not only affects the material's processing performance but also leads to fluctuations or decreases in the mechanical, insulation, and thermal conductivity properties of the finished product, limiting the application of PTFE-based cable insulation materials in high-performance fields. Therefore, improving the compatibility between insulating fillers and the PTFE matrix, and enhancing the uniformity of filler dispersion, has become a critical issue that urgently needs to be addressed in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a cable insulation layer material based on PTFE film and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a cable insulation layer material based on PTFE film includes the following steps: S1: Under a nitrogen atmosphere, 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide was added to trihexyphosphine, stirred until homogeneous, heated to 120-125℃ and reacted for 24 h, cooled to room temperature, the solid product was washed with hexane, filtered, the solid product and activated carbon were added to ethyl acetate, mixed overnight, filtered, and the solvent was evaporated to obtain the iodide salt; Furthermore, in the preparation of the iodide salt, the molar ratio of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide to trihexyphosphine is 1:(1.2-1.3). S2: Dilute the iodide salt tenfold in deionized water and pass it through an anion exchange resin column to obtain an aqueous solution of hydroxide; add heptadecafluorooctane sulfonic acid to the aqueous solution of hydroxide to neutralize the solution, evaporate and concentrate, add the crude product to acetone, pass it through a short column packed with activated alumina, evaporate and remove the acetone, and dry under vacuum at 60-65℃ to obtain a fluorine-containing ionic liquid. Furthermore, in the preparation process of the fluorine-containing ionic liquid, the molar ratio of hydroxide to heptadecafluorooctane sulfonic acid is 1:(1.1-1.2); S3: Carbon nanotubes are ultrasonically dispersed in deionized water, and organosilicon quaternary ammonium salt is added and homogenized to obtain a carbon nanotube suspension; the suspension is then vacuum filtered, and the filtered product is washed with deionized water to obtain modified carbon nanotubes; a water glass solution is added to deionized water and stirred evenly to obtain a water glass aqueous solution; the modified carbon nanotubes are ultrasonically dispersed in deionized water, and the water glass aqueous solution is added and homogenized; the suspension is then vacuum filtered, and the product is washed with deionized water. The adsorption-washing process is repeated 4-5 times, and the product is calcined at 400-405℃ for 5-6 hours to obtain water glass modified carbon nanotubes; Furthermore, in the preparation process of the carbon nanotube suspension, the mass ratio of carbon nanotubes to organosilicon quaternary ammonium salt is 1:(0.5-1); Furthermore, the water glass solution contains 28-30 wt% silica and 9-10% sodium oxide. Furthermore, the concentration of the water glass aqueous solution is 0.8-1 wt%; Furthermore, the organosilicon quaternary ammonium salt is dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride; S4: Add oleic acid to a reaction vessel, add phosphorus trichloride while stirring, heat to 55-60℃ and react for 4-4.5h to obtain oleyl chloride; add polyethylene polyamine to a reaction vessel, add oleyl chloride while stirring, react at room temperature for 1-1.5h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. Furthermore, in the preparation process of oleoyl chloride, the molar ratio of oleic acid to phosphorus trichloride is 1:1; Furthermore, in the preparation process of the bio-based compatibilizer, the mass ratio of polyethylene polyamine to oleoyl chloride is 1:(2-3); S5: Water glass modified carbon nanotubes are added to a bio-based compatibilizer, heated to 70-75℃ and stirred for 30-45 minutes to obtain an insulating filler; fluorine-containing ionic liquid is added to polytetrafluoroethylene and stirred evenly, ethylene-propylene copolymer is added and stirred evenly, insulating filler is added and stirred evenly to obtain a polytetrafluoroethylene mixture; the polytetrafluoroethylene mixture is cast and coated onto a substrate, dried, sintered, peeled off, and wound to obtain a cable insulation layer material based on PTFE film.

[0006] Furthermore, in the preparation process of the insulating filler, the mass ratio of water glass modified carbon nanotubes to bio-based compatibilizer is (30-50):1; Furthermore, the proportions of each component in the PTFE-based cable insulation layer material, by mass parts, include: 80-100 parts of polytetrafluoroethylene, 10-20 parts of fluorine-containing ionic liquid, 1-5 parts of ethylene-propylene copolymer, and 10-15 parts of insulating filler. Furthermore, the molecular weight of the polytetrafluoroethylene is 30,000-200,000.

[0007] Furthermore, the thickness of the PTFE-based cable insulation layer material is 20-200 μm; Furthermore, the film-forming drying temperature is 20-80℃; Furthermore, the sintering temperature is 350-400℃.

[0008] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention involves the self-preparation of a fluorinated ionic liquid. Utilizing its fluorine affinity and the principle of "like dissolves like," it exhibits a strong interaction with polytetrafluoroethylene (PTFE), which also contains fluorine. Some of the fluorinated ionic liquid forms micellar fluorine-rich domains composed of aggregated fluorinated alkyl chains, providing a suitable environment for the dissolution of PTFE. Furthermore, the low-polarity phosphine-cationic fluorinated ionic liquid has a weaker polar interaction with the non-polar PTFE, further enhancing their compatibility and ultimately improving the dispersibility and compatibility of the filler in the matrix.

[0009] 2. Using ethylene-acrylate copolymer as an interfacial synergist in conjunction with a prepared bio-based compatibilizer achieves the technical effect of building a "bridge". On the one hand, utilizing the anchoring effect of the -NR2 group in the bio-based solubilizer, it can be adsorbed and anchored on the surface of modified carbon nanotubes, effectively preventing the aggregation of modified carbon nanotubes and improving their dispersion uniformity in the PTFE matrix. The long hydrocarbon flexible chain can produce good compatibility with the non-polar structure of the PTFE matrix, enhancing the wetting and adhesion ability of the modified carbon nanotube surface in the PTFE matrix, thereby improving the interfacial bonding strength between modified carbon nanotubes and PTFE, reducing interfacial thermal resistance, and improving thermal conductivity. On the other hand, the addition of ethylene-acrylate copolymer further enhances the wetting and dispersion effect of modified carbon nanotubes as fillers.

[0010] 3. This invention forms a thick and uniform inorganic coating through layer-by-layer self-assembly. The modified carbon nanotubes are adsorbed by cationic precursor organosilicon quaternary ammonium salt and anionic water glass. After calcination, the organosilicon quaternary ammonium salt condenses to form the coating, which can effectively block the electronic transitions between carbon nanotubes, thereby achieving ultra-high volume resistivity. On the one hand, the coating has a good interfacial interaction with the matrix under the action of bio-based compatibilizer, reducing phonon scattering at the carbon nanotube-polymer interface and promoting thermal conduction. On the other hand, the layer-by-layer self-assembly method is a non-covalent modification that does not destroy the original highly crystalline structure of the carbon nanotubes and retains their intrinsic high thermal conductivity. The combined effect endows the PTFE film-based cable insulation material with excellent insulation and thermal conductivity. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Example 1: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S1: Under a nitrogen atmosphere, 1 mol of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide is added to 1.2 mol of trihexyphosphine, stirred evenly, heated to 120°C for 24 h, cooled to room temperature, purified, and the iodide salt is obtained; S2: Iodide salt is added to deionized water and passed through an anion exchange resin column to obtain an aqueous solution of hydroxide; 1.1 mol of heptadecafluorooctane sulfonic acid is added to an aqueous solution containing 1 mol of hydroxide, the solution is neutralized, evaporated and concentrated, and purified to obtain a fluoride-containing ionic liquid; S3: 1g of carbon nanotubes were ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt was added. The mixture was homogenized and dispersed to obtain a carbon nanotube suspension. The suspension was then vacuum filtered, and the filtered product was washed with deionized water to obtain modified carbon nanotubes. A water glass solution was added to deionized water and stirred until homogeneous to obtain a water glass aqueous solution. The modified carbon nanotubes were ultrasonically dispersed in deionized water, and the water glass aqueous solution was added. The mixture was then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process was repeated 4 times, and the mixture was calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. S4: Add 1 mmol of oleic acid to the reaction vessel, add 1 mmol of phosphorus trichloride while stirring, heat to 55°C and react for 4 h to obtain oleyl chloride; add 15 g of polyethylene polyamine to the reaction vessel, add 30 g of oleyl chloride while stirring, react at room temperature for 1 h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. S5: Add 50g of water glass modified carbon nanotubes to 1g of bio-based compatibilizer, heat to 70℃ and stir for 30min to obtain insulating filler; add 10g of fluorine-containing ionic liquid to 100g of polytetrafluoroethylene, stir evenly, add 1g of ethylene propylene copolymer, stir evenly, add 10g of insulating filler, stir evenly to obtain polytetrafluoroethylene mixture; cast the polytetrafluoroethylene mixture onto the substrate, form a film, dry, sinter, peel off, and wind up to obtain a cable insulation layer material based on PTFE film.

[0013] Example 2: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S1: Under a nitrogen atmosphere, 1 mol of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide is added to 1.2 mol of trihexylphosphine, stirred evenly, heated to 120°C for 24 h, cooled to room temperature, purified, and the iodide salt is obtained; S2: Iodide salt is added to deionized water and passed through an anion exchange resin column to obtain an aqueous solution of hydroxide; 1.1 mol of heptadecafluorooctane sulfonic acid is added to an aqueous solution containing 1 mol of hydroxide, the solution is neutralized, evaporated and concentrated, and purified to obtain a fluoride-containing ionic liquid; S3: 1g of carbon nanotubes were ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt was added. The mixture was homogenized and dispersed to obtain a carbon nanotube suspension. The suspension was then vacuum filtered, and the filtered product was washed with deionized water to obtain modified carbon nanotubes. A water glass solution was added to deionized water and stirred until homogeneous to obtain a water glass aqueous solution. The modified carbon nanotubes were ultrasonically dispersed in deionized water, and the water glass aqueous solution was added. The mixture was then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process was repeated 4 times, and the mixture was calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. S4: Add 1 mmol of oleic acid to the reaction vessel, add 1 mmol of phosphorus trichloride while stirring, heat to 55°C and react for 4 h to obtain oleyl chloride; add 15 g of polyethylene polyamine to the reaction vessel, add 30 g of oleyl chloride while stirring, react at room temperature for 1 h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. S5: Add 30g of water glass modified carbon nanotubes to 1g of bio-based compatibilizer, heat to 70℃ and stir for 30min to obtain insulating filler; add 10g of fluorine-containing ionic liquid to 100g of polytetrafluoroethylene, stir evenly, add 1g of ethylene propylene copolymer, stir evenly, add 10g of insulating filler, stir evenly to obtain polytetrafluoroethylene mixture; cast the polytetrafluoroethylene mixture onto the substrate, dry the film, sinter, peel off, and wind up to obtain a cable insulation layer material based on PTFE film.

[0014] Example 3: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S1: Under a nitrogen atmosphere, 1 mol of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide is added to 1.2 mol of trihexylphosphine, stirred evenly, heated to 120°C and reacted for 24 h, cooled to room temperature, purified, and the iodide salt is obtained; S2: Iodide salt is added to deionized water and passed through an anion exchange resin column to obtain an aqueous solution of hydroxide; 1.1 mol of heptadecafluorooctane sulfonic acid is added to an aqueous solution containing 1 mol of hydroxide, the solution is neutralized, evaporated and concentrated, and purified to obtain a fluoride-containing ionic liquid; S3: 1g of carbon nanotubes were ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt was added. The mixture was homogenized and dispersed to obtain a carbon nanotube suspension. The suspension was then vacuum filtered, and the filtered product was washed with deionized water to obtain modified carbon nanotubes. A water glass solution was added to deionized water and stirred until homogeneous to obtain a water glass aqueous solution. The modified carbon nanotubes were ultrasonically dispersed in deionized water, and the water glass aqueous solution was added. The mixture was then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process was repeated 4 times, and the mixture was calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. S4: Add 1 mmol of oleic acid to the reaction vessel, add 1 mmol of phosphorus trichloride while stirring, heat to 55°C and react for 4 h to obtain oleyl chloride; add 15 g of polyethylene polyamine to the reaction vessel, add 30 g of oleyl chloride while stirring, react at room temperature for 1 h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. S5: Add 30g of water glass modified carbon nanotubes to 1g of bio-based compatibilizer, heat to 70℃ and stir for 30min to obtain insulating filler; add 15g of fluorine-containing ionic liquid to 100g of polytetrafluoroethylene, stir evenly, add 3g of ethylene propylene copolymer, stir evenly, add 10g of insulating filler, stir evenly to obtain polytetrafluoroethylene mixture; cast the polytetrafluoroethylene mixture onto the substrate, form a film, dry, sinter, peel off, and wind up to obtain a cable insulation layer material based on PTFE film.

[0015] Example 4: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S1: Under a nitrogen atmosphere, 1 mol of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide is added to 1.2 mol of trihexyphosphine, stirred evenly, heated to 120°C and reacted for 24 h, cooled to room temperature, purified, and the iodide salt is obtained; S2: Iodide salt is added to deionized water and passed through an anion exchange resin column to obtain an aqueous solution of hydroxide; 1.1 mol of heptadecafluorooctane sulfonic acid is added to an aqueous solution containing 1 mol of hydroxide, the solution is neutralized, evaporated and concentrated, and purified to obtain a fluoride-containing ionic liquid; S3: 1g of carbon nanotubes were ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt was added. The mixture was homogenized and dispersed to obtain a carbon nanotube suspension. The suspension was then vacuum filtered, and the filtered product was washed with deionized water to obtain modified carbon nanotubes. A water glass solution was added to deionized water and stirred until homogeneous to obtain a water glass aqueous solution. The modified carbon nanotubes were ultrasonically dispersed in deionized water, and the water glass aqueous solution was added. The mixture was then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process was repeated 4 times, and the mixture was calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. S4: Add 1 mmol of oleic acid to the reaction vessel, add 1 mmol of phosphorus trichloride while stirring, heat to 55°C and react for 4 h to obtain oleyl chloride; add 15 g of polyethylene polyamine to the reaction vessel, add 30 g of oleyl chloride while stirring, react at room temperature for 1 h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. S5: Add 30g of water glass modified carbon nanotubes to 1g of bio-based compatibilizer, heat to 70℃ and stir for 30min to obtain insulating filler; add 20g of fluorine-containing ionic liquid to 100g of polytetrafluoroethylene, stir evenly, add 5g of ethylene propylene copolymer, stir evenly, add 15g of insulating filler, stir evenly to obtain polytetrafluoroethylene mixture; cast the polytetrafluoroethylene mixture onto the substrate, dry the film, sinter, peel off, and wind up to obtain a cable insulation layer material based on PTFE film.

[0016] Comparative Example 1: A method for preparing a cable insulation layer material based on PTFE film, comprising the following steps: S5: 50g of water glass modified carbon nanotubes are added to 1g of bio-based compatibilizer, heated to 70℃ and stirred for 30min to obtain an insulating filler; 100g of polytetrafluoroethylene is dispersed in 30g of deionized water, 10g of silicone oil is added, stirred evenly, 1g of ethylene propylene copolymer is added, stirred evenly, 10g of insulating filler is added, stirred evenly to obtain a polytetrafluoroethylene mixture; the polytetrafluoroethylene mixture is cast and coated on a substrate, dried, sintered, peeled off, and wound up to obtain a cable insulation layer material based on PTFE film.

[0017] The remaining steps are the same as in Example 1.

[0018] Comparative Example 2: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S1: Under a nitrogen atmosphere, 1 mol of 1,2-dimethylimidazolium is dissolved in acetonitrile, added to 1.2 mol of 1-bromobutane, stirred evenly, heated to 70℃ for 48 h, cooled to room temperature, purified, and bromide salt is obtained; S2: Add bromide salt to deionized water and pass it through an anion exchange resin column to obtain an aqueous solution of hydroxide; add 1.1 mol of trifluoromethanesulfonic acid to an aqueous solution containing 1 mol of hydroxide, neutralize the solution, evaporate and concentrate, and purify to obtain a fluoride-containing ionic liquid; S3: 1g of carbon nanotubes were ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt was added. The mixture was homogenized and dispersed to obtain a carbon nanotube suspension. The suspension was then vacuum filtered, and the filtered product was washed with deionized water to obtain modified carbon nanotubes. A water glass solution was added to deionized water and stirred until homogeneous to obtain a water glass aqueous solution. The modified carbon nanotubes were ultrasonically dispersed in deionized water, and the water glass aqueous solution was added. The mixture was then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process was repeated 4 times, and the mixture was calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. S4: Add 1 mmol of oleic acid to the reaction vessel, add 1 mmol of phosphorus trichloride while stirring, heat to 55°C and react for 4 h to obtain oleyl chloride; add 15 g of polyethylene polyamine to the reaction vessel, add 30 g of oleyl chloride while stirring, react at room temperature for 1 h, add deionized water, stir evenly, filter, wash the product with deionized water until neutral to obtain a bio-based compatibilizer. S5: Add 50g of water glass modified carbon nanotubes to 1g of bio-based compatibilizer, heat to 70℃ and stir for 30min to obtain insulating filler; add 10g of fluorine-containing ionic liquid to 100g of polytetrafluoroethylene, stir evenly, add 1g of ethylene propylene copolymer, stir evenly, add 10g of insulating filler, stir evenly to obtain polytetrafluoroethylene mixture; cast the polytetrafluoroethylene mixture onto the substrate, form a film, dry, sinter, peel off, and wind up to obtain a cable insulation layer material based on PTFE film.

[0019] Comparative Example 3: A method for preparing a cable insulation layer material based on PTFE film: including the following steps: S3: 1g of carbon nanotubes are ultrasonically dispersed in 800mL of deionized water, and 200mL of a solution containing 0.5g of organosilicon quaternary ammonium salt is added. The mixture is homogenized and dispersed to obtain a carbon nanotube suspension. The suspension is then vacuum filtered, and the filtered product is washed with deionized water to obtain modified carbon nanotubes. A water glass solution is added to deionized water and stirred evenly to obtain a water glass aqueous solution. The modified carbon nanotubes are ultrasonically dispersed in deionized water, and the water glass aqueous solution is added. The mixture is then homogenized and dispersed, vacuum filtered, and washed with deionized water. The adsorption-washing process is repeated 6 times, and the mixture is calcined at 400℃ for 5h to obtain water glass modified carbon nanotubes. The remaining steps are the same as in Example 1.

[0020] Comparative Example 4: A method for preparing a cable insulation layer material based on PTFE film, comprising the following steps: S5: 50g of water glass modified carbon nanotubes are added to 1g of bio-based compatibilizer, heated to 70℃ and stirred for 30min to obtain insulating filler; 10g of fluorine-containing ionic liquid is added to 100g of polytetrafluoroethylene, stirred evenly, 10g of insulating filler is added, stirred evenly to obtain polytetrafluoroethylene mixture; the polytetrafluoroethylene mixture is cast and coated on a substrate, dried to form a film, sintered, peeled off, and wound up to obtain a cable insulation layer material based on PTFE film.

[0021] Experiment: Volume resistivity: The thin film samples prepared in the above examples and comparative examples were measured using a high resistance meter. A voltage of 100V was applied, and the reading was taken after 20s. The average value of the three readings was taken.

[0022] Thermal conductivity: The thin film samples prepared in the above examples and comparative examples were measured at 40°C using a steady-state method, and the average value of three measurements was taken.

[0023] The experimental data are shown in Table 1 below.

[0024] Table 1 Test data of cable insulation material based on PTFE film

[0025] Conclusion: The PTFE film-based cable insulation material prepared by this invention has excellent insulation and thermal conductivity.

[0026] In Comparative Example 1, deionized water was used instead of the fluorinated ionic liquid of this application, resulting in reduced dispersibility and compatibility, and a decrease in the performance of the PTFE membrane-based cable insulation material.

[0027] In Comparative Example 2, fluorine-containing ionic liquids were prepared using 1,2-dimethylimidazole, a highly polar substance, as a raw material. This resulted in stronger interactions, reduced dispersion and compatibility, and consequently, decreased performance of the PTFE-based cable insulation material.

[0028] In Comparative Example 3, the excessively thick self-coating layers on the surface of the modified nanotubes resulted in a significant decrease in thermal conductivity due to increased phonon scattering.

[0029] The lack of ethylene-propylene copolymer as an interface synergist in Comparative Example 4 resulted in reduced dispersibility and compatibility, leading to a decrease in the performance of the PTFE-based cable insulation material.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a cable insulation layer material based on PTFE film, characterized in that: Includes the following steps: Water glass-modified carbon nanotubes were added to a bio-based compatibilizer and heated to 70-75℃ and stirred for 30-45 minutes to obtain an insulating filler. Fluorine-containing ionic liquid was added to polytetrafluoroethylene and stirred evenly. Ethylene-propylene copolymer was added and stirred evenly. The insulating filler was added and stirred evenly to obtain a polytetrafluoroethylene mixture. The polytetrafluoroethylene mixture was cast and coated onto a substrate, dried, sintered, peeled off, and wound up to obtain a cable insulation layer material based on a PTFE film.

2. The method for preparing a cable insulation layer material based on PTFE film according to claim 1, characterized in that: In the preparation of insulating fillers, the mass ratio of water glass modified carbon nanotubes to bio-based compatibilizer is (30-50):

1.

3. The method for preparing a cable insulation layer material based on PTFE film according to claim 1, characterized in that: The components of the PTFE-based cable insulation material, by mass, include: 80-100 parts polytetrafluoroethylene, 10-20 parts fluorine-containing ionic liquid, 1-5 parts ethylene-propylene copolymer, and 10-15 parts insulating filler.

4. The method for preparing a cable insulation layer material based on PTFE film according to claim 1, characterized in that: The method for preparing water glass modified carbon nanotubes includes the following steps: ultrasonically dispersing carbon nanotubes in deionized water, adding organosilicon quaternary ammonium salt, homogenizing and dispersing to obtain a carbon nanotube suspension; vacuum filtering, washing the filtered product with deionized water to obtain modified carbon nanotubes; adding water glass solution to deionized water, stirring evenly to obtain a water glass aqueous solution; ultrasonically dispersing modified carbon nanotubes in deionized water, adding water glass aqueous solution, homogenizing and dispersing, vacuum filtering, washing with deionized water, repeating the adsorption-washing process 4-5 times, and calcining at 400-405℃ for 5-6 hours to obtain water glass modified carbon nanotubes; In the preparation of carbon nanotube suspension, the mass ratio of carbon nanotubes to organosilicon quaternary ammonium salt is 1:(0.5-1).

5. The method for preparing a cable insulation layer material based on PTFE film according to claim 1, characterized in that: The preparation method of the bio-based compatibilizer includes the following steps: oleic acid is added to a reaction vessel, phosphorus trichloride is added under stirring, and the mixture is heated to 55-60℃ for 4-4.5 h to obtain oleyl chloride; polyethylene polyamine is added to a reaction vessel, oleyl chloride is added under stirring, the mixture is reacted at room temperature for 1-1.5 h, deionized water is added, the mixture is stirred evenly, filtered, and the product is washed with deionized water until neutral to obtain the bio-based compatibilizer; In the preparation of oleyl chloride, the molar ratio of oleic acid to phosphorus trichloride is 1:1; In the preparation of bio-based compatibilizers, the mass ratio of polyethylene polyamine to oleoyl chloride is 1:(2-3).

6. The method for preparing a cable insulation layer material based on PTFE film according to claim 1, characterized in that: The method for preparing the fluorine-containing ionic liquid includes the following steps: adding iodide salt to deionized water and passing it through an anion exchange resin column to obtain an aqueous solution of hydroxide; adding heptadecafluorooctane sulfonic acid to the aqueous solution of hydroxide, neutralizing the solution, evaporating and concentrating, and purifying to obtain the fluorine-containing ionic liquid; In the preparation of fluorine-containing ionic liquids, the molar ratio of hydroxide to heptadecafluorooctane sulfonic acid is 1:(1.1-1.2).

7. The method for preparing a cable insulation layer material based on a PTFE film according to claim 6, characterized in that: The method for preparing the iodide salt includes the following steps: under a nitrogen atmosphere, 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptafluoroundecyl iodide is added to trihexyphosphine, stirred evenly, heated to 120-125℃ for 24 h, cooled to room temperature, and purified to obtain the iodide salt; In the preparation of iodide salts, the molar ratio of 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecylfluoroundecyl iodide to trihexyphosphine is 1:(1.2-1.3).

8. The cable insulation material based on PTFE film prepared according to any one of claims 1-7.

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