Aging-resistant cloth wire with low conductive loss

Abstract

The application discloses an aging-resistant cloth electric wire with low conductive loss and belongs to the technical field of electric wires and cables. The application mainly aims at the technical problem of how to further optimize the conductive loss, heat aging resistance and mechanical properties of the cloth electric wire. The cloth electric wire comprises a conductive core and an outer sheath layer. The outer sheath layer comprises the following components in parts by weight: 100 parts of polyvinyl chloride, 4-6 parts of polydimethylsiloxane-coated polyimide aerogel, 4-5 parts of fluorine-modified copolymer polysiloxane, 8-12 parts of aromatic-modified copolymer saturated polyester and 4.1-5.8 parts of auxiliary additives. The application further improves the conductive loss, heat aging resistance and mechanical properties of the prepared cloth electric wire through the synergistic effect among the prepared polydimethylsiloxane-coated polyimide aerogel, fluorine-modified copolymer polysiloxane and aromatic-modified copolymer saturated polyester.

Description

Technical Field

[0001] This invention relates to the field of wire and cable technology, and specifically to a low-conductivity-loss, aging-resistant fabric wire. Background Technology

[0002] With the rapid development of smart grids and high-end equipment manufacturing, the performance requirements of power transmission cables, as the "blood vessels" of power transmission, have shifted from a single conductive function to multifunctionality and high performance. Modern power transmission cables not only require excellent conductivity to reduce transmission loss, but also need to maintain long-term stability under complex working conditions. Especially in high-frequency, high-voltage, and high-temperature environments, the dielectric loss factor of cable insulation and sheath materials directly affects power transmission efficiency and heat generation. High dielectric loss can lead to cable temperature rise, accelerate insulation aging, and even cause thermal breakdown. Therefore, developing power transmission cables with low dielectric loss, high heat aging resistance, and excellent mechanical properties has become the core direction for the technological upgrading of the current cable industry.

[0003] Currently, polyvinyl chloride (PVC) is widely used as a material for sheathing electrical wires due to its low cost and good flame retardancy. However, the PVC molecular chain contains highly polar carbon-chlorine bonds, resulting in high dielectric loss and poor heat resistance. It is prone to degradation due to dehydrochlorination reaction when heated for a long time. To improve this defect, inorganic fillers or blended elastomers are often added for modification. Although these methods improve mechanical strength or toughness to some extent, the high surface energy of inorganic fillers can easily lead to agglomeration and poor compatibility with the PVC matrix. They can easily form micropores at the interface, which can aggravate interfacial polarization and cause dielectric loss to increase instead of decrease. Conventional elastomer modification often sacrifices the heat resistance of the material and cannot simultaneously meet the dual requirements of low loss and aging resistance.

[0004] In response to the aforementioned technical bottlenecks, this solution aims to address the technical challenge of balancing the reduction of media loss and the improvement of heat aging resistance in traditional PVC sheath materials. Summary of the Invention

[0005] The purpose of this invention is to provide a low-conductivity-loss, aging-resistant electrical wire to solve the above-mentioned technical defects.

[0006] The objective of this invention can be achieved through the following technical solution: an aging-resistant building wire with low conductivity loss, comprising a conductive core and an outer sheath layer;

[0007] The outer sheath layer comprises the following components by weight: 100 parts polyvinyl chloride, 4-6 parts polymethylsiloxane-coated polyimide aerogel, 4-5 parts fluorine-modified copolymer polysiloxane, 8-12 parts aromatic-modified copolymer saturated polyester, 0.8-1.5 parts polyethylene grafted glycidyl methacrylate, 0.05-0.15 parts chlorinated polyethylene, and 4.1-5.8 parts auxiliary additives;

[0008] The polymethylsiloxane-coated polyimide aerogel is prepared by polycondensation, crosslinking and imidization of 4,4′-diaminodiphenyl ether and 1,3,5-tris(4-aminophenoxy)benzene with hexafluorodianhydride to form a polyimide aerogel matrix, which is then coated in situ by hydrolysis and condensation of methyltrimethoxysilane.

[0009] Furthermore, the polymethylsiloxane-coated polyimide aerogel is prepared by the following steps:

[0010] A1. Add 4,4'-diaminodiphenyl ether to a reaction vessel containing N-methylpyrrolidone and stir until completely dissolved. Then add hexafluorodianhydride and stir for 40-60 min. Next, add a solution of 1,3,5-tris(4-aminophenoxy)benzene in N-methylpyrrolidone and stir for 5-10 min. Then add propionic anhydride and pyridine and stir for 10-20 min. Pour the mixture into a mold, seal it, and let it stand until gelled. Seal it with anhydrous ethanol and age it at 75°C for 2-3 days. Then, perform solvent replacement 2-3 times with anhydrous ethanol. Then, transfer the gel to a supercritical carbon dioxide drying vessel, heat it to 50-60°C, pressurize it to 12-13 MPa, and dry it for about 7-8 h. After cooling to room temperature, remove it, pulverize it, and pass it through a 500-mesh sieve to obtain a polyimide aerogel matrix.

[0011] A2. Add methyltrimethoxysilane, urea, acetic acid, and hexadecyltrimethylammonium bromide to a reactor containing deionized water and stir for 40-60 minutes. Then add polyimide aerogel matrix and impregnate at 50-60°C for 20-24 hours. After solvent replacement with anhydrous ethanol 2-3 times, transfer the gel to a supercritical carbon dioxide drying reactor, heat to 50-60°C, pressurize to 12-13 MPa and dry for about 7-8 hours. After cooling to room temperature, remove the gel, pulverize it, and pass it through a 500-mesh sieve to obtain polymethylsiloxane-coated polyimide aerogel.

[0012] Further, in step A1, the ratio of the amounts of 4,4'-diaminodiphenyl ether, N-methylpyrrolidone, hexafluorodianhydride, the N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene, propionic anhydride, and pyridine is 2g:50-55mL:4.5g:5mL:10.4-10.5mL:6.5mL, wherein the mass fraction of the N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene is 0.87%; in step A2, the ratio of the amounts of methyltrimethoxysilane, urea, acetic acid, hexadecyltrimethylammonium bromide, deionized water, and polyimide aerogel matrix is ​​13.0-13.3g:10g:0.02mL:0.6g:60mL:2.5g.

[0013] Furthermore, the preparation method of the fluorine-modified copolysiloxane is as follows: under a nitrogen atmosphere, trifluoropropylmethylcyclotrisiloxane and octamethylcyclotetrasiloxane are added to a reaction vessel and stirred at 70-90°C for 20-30 min. Then, 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide are added. After reacting at 90-110°C for 5-6 h, the temperature is first raised to 140-150°C and reacted for 40-60 min, and then the temperature is further raised to 1... After stirring at 60-180℃ under a vacuum of 0.5-1kPa for 1-2 hours, the reaction is completed. Heating is then stopped, and the mixture is cooled to 20-30℃. Ethyl acetate is added and stirred until completely dissolved. Then, 3-4 times the volume of anhydrous methanol is added, and the mixture is stirred for 5-10 minutes. After standing for 10-20 minutes, the mixture is separated, and the lower oily layer is collected. The oil is washed 2-3 times with anhydrous methanol and then transferred to a vacuum drying oven. The mixture is dried at 50-60℃ for 6-8 hours to obtain fluorine-modified copolysiloxane.

[0014] The reaction formula for preparing fluorine-modified copolysiloxanes is as follows:

[0015]

[0016] Furthermore, the ratio of the amounts of trifluoropropylmethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide is 10g:90g:1.43-1.47g:0.08g.

[0017] Furthermore, the preparation method of the aromatic modified copolysaturated polyester is as follows: Under a nitrogen atmosphere, phthalic anhydride, 1,4-cyclohexanediol, 1,6-hexanediol and tetrabutyl titanate are added to a reaction vessel, heated to 130-140℃ and stirred for 40-60 minutes to melt and mix the raw materials. Then, the temperature is raised to 150-165℃ and reacted for 1-2 hours. Subsequently, the temperature is raised to 180-190℃ and reacted for 2-3 hours. Then, the temperature is raised to 195-205℃ and reacted until the acid value drops to 4-5 mg KOH / g. The temperature is raised to 210-230℃, and the pressure is gradually reduced to 0.5-1.0 kPa and reacted for 1-2 hours. When the acid value drops to 1.0-1.5 mg KOH / g, heating is stopped. After the reaction system cools down, the product is discharged and placed in a vacuum drying oven and dried at 80-100℃ for 6-8 hours to obtain the aromatic modified copolysaturated polyester.

[0018] The reaction formula for preparing aromatic modified copolysaturated polyesters:

[0019]

[0020] In the formula:

[0021]

[0022] Furthermore, the ratio of 1,4-cyclohexanediol, 1,6-hexanediol, and tetrabutyl titanate is 55g:45g:0.043g, and the amount of phthalic anhydride added is 0.52 times the total molar amount of hydroxyl groups in 1,4-cyclohexanediol and 1,6-hexanediol.

[0023] Furthermore, the preparation method of the low conductivity loss aging-resistant fabric wire is as follows: Polyvinyl chloride, polyethylene grafted with glycidyl methacrylate, chlorinated polyethylene and auxiliary additives are added to a high-speed mixer and mixed at a speed of 800-1000 r / min for 3-5 min. Then, polymethylsiloxane-coated polyimide aerogel, fluorine-modified copolymer polysiloxane and aromatic-modified copolymer saturated polyester are added and mixed for another 5-8 min. The mixture is then transferred to a twin-screw extruder, melted and extruded to coat the outside of the conductive core. After coating, the wire is initially cooled with warm water at 50-60℃, then cooled and shaped with cold water at 20-25℃, and then dried with hot air. After cooling, the low conductivity loss aging-resistant fabric wire is obtained.

[0024] Furthermore, the conductive core is copper wire; in step S2, the temperatures of the six temperature zones set from the feed end toward the die head of the twin-screw extruder are sequentially set to 185℃, 190℃, 195℃, 195℃, 190℃, and 190℃, and the spindle speed of the twin-screw extruder is 30-40 r / min.

[0025] The present invention has the following beneficial effects:

[0026] 1. The polymethylsiloxane-coated polyimide aerogel of this invention is rich in a nanoporous hollow framework. The Si-O low-polarity structure of the outer layer of siloxane isolates the polar imide groups of the aerogel. The porous structure can bind the free polarization charge in the system, weakening the dipole polarization loss under alternating electric field from the matrix level. The fluorine-modified copolymer polysiloxane molecular chain introduces a large number of low-polarity CF bonds. The strong electronegativity of fluorine atoms can fix the molecular dipole and suppress the directional shift of groups under electric field, weakening the interfacial polarization. The carboxyl groups at both ends of the aromatic-modified copolymer saturated polyester molecule can form hydrogen bond crosslinks with the hydroxyl groups on the surface of PVC matrix and siloxane filler, respectively, eliminating micro gaps between filler and matrix and reducing interfacial defect polarization. After the three are combined, the aerogel undertakes the function of low dielectric framework, the fluorine and silicon components reduce the intrinsic polarity of the molecules, and the aromatic polyester acts as a compatible bridge to eliminate two-phase dielectric defects. The multi-layer structure synergistically reduces the overall dielectric loss factor of the sheath, effectively reducing the dielectric heating loss of electrical energy conversion during cable operation, and achieving the core advantage of low conductivity loss.

[0027] 2. The Si-O bond energy of the polymethylsiloxane coating layer of this invention is much higher than that of the carbon chain, making it less prone to breakage and decomposition at high temperatures. It can encapsulate the porous polyimide framework to isolate oxygen and moisture from penetrating the interior, preventing high-temperature oxidation and deterioration of the aerogel framework. The CF bond of the fluorinated copolymer polysiloxane has extremely strong chemical inertness, making it less prone to chain breakage and oxidation to generate polar byproducts under long-term thermal conditions. At the same time, the fluorinated silicon segments migrate to the surface of the sheath to form a dense and weather-resistant protective film, blocking the thermal and oxygen erosion of the PVC matrix and inhibiting the dehydrochlorination reaction of PVC. The aromatic modified copolymer saturated polyester molecules contain rigid benzene rings and cyclohexane structures, making the molecular chains less prone to slippage and degradation at high temperatures. The terminal carboxyl groups can capture the active free radicals generated by the thermal decomposition of PVC, delaying the aging of the matrix. The three elements work together to construct a triple protection of an internal anti-decomposition framework, a surface inert protective film, and a free radical capture buffer layer. During thermal aging, the amount of polar groups generated by the molecules is greatly reduced, the increase in dielectric loss is significantly reduced, and the degree of mechanical property degradation after thermal aging is significantly slowed down, resulting in a significant improvement in long-term high-temperature service stability.

[0028] 3. The rigid cross-linked polyimide skeleton of the polymethylsiloxane-coated polyimide aerogel of the present invention serves as a nano-reinforcing unit, uniformly dispersed within the PVC matrix. Under stress, it can disperse external stress, block the propagation of microcracks, and improve the overall tensile strength. The fluorinated copolymer polysiloxane has a long flexible siloxane main chain and side fluoroalkyl groups, which serve as a flexible toughening phase interspersed between the matrix and the filler. Under stress, it absorbs impact energy through the expansion of the silicon chains, improving the elongation at break and toughness of the material. The aromatic copolymer saturated polyester has both a rigid cyclic structure and a flexible aliphatic chain, serving as an interfacial compatibility medium. One end is bonded to the polar molecular chain of PVC, and the other end is bonded to the surface groups of the siloxane filler, solving the defects of poor compatibility between organosilicon fillers and PVC and easy phase separation and cracking. The rigid aerogel reinforcement, the fluorosilicone flexible chain toughening, and the aromatic polyester bridging interface work synergistically to avoid the material embrittlement and strength reduction caused by a single filler, while simultaneously improving the tensile strength and ductility of the sheath. After molding, the tensile and crack resistance of the sheath is significantly improved. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0030] In this application, the polyvinyl chloride is a commercially available product, model PA5470 / 5;

[0031] In this application, the polyethylene grafted glycidyl methacrylate is a commercially available product with the model number XH7250X0OIKV;

[0032] In this application, chlorinated polyethylene is a commercially available product, model CPE;

[0033] In this application, the copper wire has a specification of 5mm and a conductivity of 99.96%.

[0034] Example 1

[0035] This embodiment provides a method for preparing a low-conductivity, aging-resistant electrical wire, including the following steps:

[0036] S1. Preparation of polymethylsiloxane-coated polyimide aerogel

[0037] Weigh 100g of 4,4'-diaminodiphenyl ether and add it to a reaction vessel containing 2500mL of N-methylpyrrolidone. Stir until completely dissolved, then add 225g of hexafluorodianhydride and stir for 40min. Next, add 250mL of 0.87wt% N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene and stir for 5min. Then add 520mL of propionic anhydride and 325mL of pyridine and stir for 10min. Pour the mixture into a mold, seal and let it stand until gelled. Seal with anhydrous ethanol and age at 75℃ for 2 days. Then perform two solvent replacements with anhydrous ethanol. Transfer the gel to a supercritical carbon dioxide drying vessel, heat to 50℃ and pressurize to 12MPa to dry for about 7h. After cooling to room temperature, remove the gel, pulverize it, and pass it through a 500-mesh sieve to obtain a polyimide aerogel matrix.

[0038] Weigh out 130g of methyltrimethoxysilane, 100g of urea, 0.2mL of acetic acid and 6g of hexadecyltrimethylammonium bromide and add them to a reactor containing 600mL of deionized water. After stirring for 40min, add 25g of polyimide aerogel matrix and impregnate at 50℃ for 20h. After two solvent replacements with anhydrous ethanol, transfer the gel to a supercritical carbon dioxide drying reactor, heat to 50℃ and pressurize to 12MPa to dry for about 7h. After cooling to room temperature, remove the gel, pulverize it and pass it through a 500-mesh sieve to obtain polymethylsiloxane-coated polyimide aerogel.

[0039] Reaction mechanism for preparing polymethylsiloxane-coated polyimide aerogels:

[0040] During the reaction, the primary amino group of 4,4'-diaminodiphenyl ether undergoes nucleophilic addition to hexafluorodianhydride for ring-opening, followed by polycondensation to form a polyamic acid chain. The polyamino groups of 1,3,5-tris(4-aminophenoxy)benzene initiate the branching and cross-linking of the molecular chain. Under the catalysis of propionic anhydride and pyridine, the amic acid group undergoes dehydration and ring closure to form a five-membered imide ring, constructing a cross-linked polyimide gel framework. Subsequently, methyltrimethoxysilane hydrolyzes in an acidic aqueous phase to form silanol groups. The silanol groups intermittently condense with methoxy groups to form polymethylsiloxane oligomers and nanoparticles. These hydrolysis products enter the pores of the polyimide aerogel, where the silanol groups on their surface form hydrogen bonds and physical cross-links with the carbonyl groups in the polyimide framework, inducing the polymethylsiloxane nanoparticles to nucleate, grow, and interconnect in situ along the framework, ultimately forming an organic-inorganic composite network structure in which a dense polymethylsiloxane nanolayer encapsulates the polyimide framework.

[0041] S2, Preparation of fluorine-modified copolysiloxane

[0042] Under a nitrogen atmosphere, 100g of trifluoropropylmethylcyclotrisiloxane and 900g of octamethylcyclotetrasiloxane were weighed and added to a reaction vessel. The mixture was stirred at 70°C for 20 min. Then, 14.3g of 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and 0.8g of tetramethylammonium hydroxide were added and reacted at 90°C for 5 h. The temperature was then raised to 140°C and reacted for 40 min. The temperature was then raised to 160°C and stirred for 1 h under a vacuum of 0.5 kPa. After the reaction was completed, the heating was stopped and the mixture was cooled to 20°C. Ethyl acetate was added and stirred until completely dissolved. Then, three volumes of anhydrous methanol were added and stirred for 5 min. The mixture was allowed to stand for 10 min, and the liquid was separated. The lower oily layer was collected, washed twice with anhydrous methanol, and then transferred to a vacuum drying oven and dried at 50°C for 6 h to obtain fluorine-modified copolymer polysiloxane.

[0043] Reaction mechanism for the preparation of fluorine-modified copolysiloxanes:

[0044] Under the action of an alkaline catalyst, cyclic siloxane monomers undergo nucleophilic ring-opening to generate active silanolate intermediates, which then copolymerize with chloropropyl-containing linear disiloxanes. Through the breaking and recombination of siloxane bonds, fluorinated side groups and terminal chloropropyl groups are introduced into the polymer backbone to form random or block copolymer structures. Subsequently, under high temperature and high vacuum conditions, residual cyclic monomers and low-boiling-point byproducts in the system are removed, while the polymerization reaction is shifted towards the formation of high molecular weight products, and the catalyst is thermally deactivated. Finally, by solvent dissolution and alcohol washing, the difference in solubility of products and impurities in polar solvents is utilized to effectively remove residual catalysts, unreacted monomers, and oligomers, thereby obtaining pure fluorinated copolymer polysiloxanes.

[0045] S3. Preparation of aromatic-modified copolysaturated polyester

[0046] Under a nitrogen atmosphere, 550g of 1,4-cyclohexanediethanol, 450g of 1,6-hexanediol, the amount of phthalic anhydride to be added (calculated as 0.52 times the total molar amount of hydroxyl groups in 1,4-cyclohexanediethanol and 1,6-hexanediol), and 0.43g of tetrabutyl titanate were weighed and added to a reactor. The mixture was heated to 130℃ and stirred for 40 minutes to melt and mix the raw materials. The temperature was then raised to 150℃ and reacted for 1 hour, followed by a reaction at 180℃ for 2 hours. The temperature was then raised to 195℃ and reacted until the acid value dropped to 4 mg KOH / g. The temperature was then raised to 210℃ and gradually reduced to 0.5 kPa for 1 hour. When the acid value dropped to 1.0 mg KOH / g, heating was stopped. After the reaction system cooled down, the product was discharged and placed in a vacuum drying oven and dried at 80℃ for 6 hours to obtain an aromatic modified copolysaturated polyester.

[0047] Reaction mechanism for preparing aromatic-modified copolysaturated polyesters:

[0048] Under inert gas protection, phthalic anhydride is first subjected to nucleophilic attack by the hydroxyl groups in 1,4-cyclohexanediol and 1,6-hexanediol, resulting in ring-opening of the anhydride ring and the formation of phthalic acid monoesters containing carboxyl and hydroxyl groups. Further diesters and low-polyester intermediates are then formed. As the system gradually heats up, under the catalysis of tetrabutyl titanate, esterification condensation and transesterification polymerization reactions of carboxyl and hydroxyl groups continue to occur between intermediates and between intermediates and unreacted monomers, continuously forming new ester bonds and removing water, causing the molecular chains to gradually grow. In the later stages of the reaction, residual water and other volatile small molecules are removed in time through high temperature and gradual decompression, allowing the polymerization equilibrium to continuously shift towards the high molecular weight direction. Finally, because the carboxyl equivalent of phthalic anhydride is slightly higher than the hydroxyl equivalent of the diol, a linear saturated polyester with carboxyl groups at the end is obtained.

[0049] S4. Prepare aging-resistant building wires with low conductivity loss.

[0050] Weigh out 3 parts by weight of epoxidized soybean oil, 0.5 parts of antioxidant 1010 and 0.6 parts of calcium stearate, mix them evenly to obtain the auxiliary additive;

[0051] Weigh out 100 parts by weight of polyvinyl chloride, 0.8 parts by weight of polyethylene grafted glycidyl methacrylate, 0.05 parts by weight of chlorinated polyethylene, and 4.1 parts by weight of auxiliary additives and add them to a high-speed mixer. Mix at 800 r / min for 3 min. Then add 4 parts by weight of polymethylsiloxane-coated polyimide aerogel, 4 parts by weight of fluorine-modified copolymer polysiloxane, and 8 parts by weight of aromatic-modified copolymer saturated polyester. Continue mixing for 5 min and then transfer to a twin-screw extruder. The twin-screw extruder has 6 temperature zones set from the feed end to the die head, with temperatures of 185℃, 190℃, 195℃, 195℃, 190℃, and 190℃ respectively. The spindle speed is 30 r / min. After melting, the extruded material is coated onto the outside of the copper wire conductive core. After coating, the material is initially cooled with 50℃ warm water, then cooled and shaped with 20℃ cold water, and then dried with hot air. After cooling, a low-conductivity, aging-resistant fabric wire is obtained.

[0052] Example 2

[0053] This embodiment provides a method for preparing a low-conductivity, aging-resistant electrical wire, including the following steps:

[0054] S1. Preparation of polymethylsiloxane-coated polyimide aerogel

[0055] Weigh 100g of 4,4'-diaminodiphenyl ether and add it to a reaction vessel containing 2750mL of N-methylpyrrolidone. Stir until completely dissolved, then add 225g of hexafluorodianhydride and stir for 60min. Next, add 250mL of 0.87wt% N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene and stir for 10min. Then add 525mL of propionic anhydride and 325mL of pyridine and stir for 20min. Pour the mixture into a mold, seal and let it stand until gelled. Seal with anhydrous ethanol and age at 75℃ for 3 days. Then perform three solvent replacements with anhydrous ethanol. Transfer the gel to a supercritical carbon dioxide drying vessel, heat to 60℃ and pressurize to 13MPa to dry for about 8h. After cooling to room temperature, remove the gel, pulverize it, and pass it through a 500-mesh sieve to obtain a polyimide aerogel matrix.

[0056] Weigh out 133g of methyltrimethoxysilane, 100g of urea, 0.2mL of acetic acid and 6g of hexadecyltrimethylammonium bromide and add them to a reactor containing 600mL of deionized water. After stirring for 60min, add 25g of polyimide aerogel matrix and impregnate at 60℃ for 24h. After solvent replacement with anhydrous ethanol three times, transfer the gel to a supercritical carbon dioxide drying reactor, heat to 60℃ and pressurize to 13MPa to dry for about 8h. After cooling to room temperature, remove the gel, pulverize it and pass it through a 500-mesh sieve to obtain polymethylsiloxane-coated polyimide aerogel.

[0057] S2, Preparation of fluorine-modified copolysiloxane

[0058] Under a nitrogen atmosphere, 100g of trifluoropropylmethylcyclotrisiloxane and 900g of octamethylcyclotetrasiloxane were weighed and added to a reaction vessel. The mixture was stirred at 90°C for 30 min. Then, 14.7g of 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and 0.8g of tetramethylammonium hydroxide were added and reacted at 110°C for 6 h. The temperature was then raised to 150°C and reacted for 60 min. The temperature was then raised to 180°C and stirred for 2 h under a vacuum of 1 kPa. After the reaction was completed, the heating was stopped and the mixture was cooled to 30°C. Ethyl acetate was added and stirred until completely dissolved. Then, 4 volumes of anhydrous methanol were added and stirred for 10 min. The mixture was allowed to stand for 20 min, and the liquid was separated. The lower oily layer was collected, washed three times with anhydrous methanol, and then transferred to a vacuum drying oven and dried at 60°C for 8 h to obtain fluorine-modified copolymer polysiloxane.

[0059] S3. Preparation of aromatic-modified copolysaturated polyester

[0060] Under a nitrogen atmosphere, 550g of 1,4-cyclohexanediethanol, 450g of 1,6-hexanediol, the amount of phthalic anhydride to be added (calculated as 0.52 times the total molar amount of hydroxyl groups in 1,4-cyclohexanediethanol and 1,6-hexanediol), and 0.43g of tetrabutyl titanate were weighed and added to a reactor. The mixture was heated to 140℃ and stirred for 60 minutes to melt and mix the raw materials. The temperature was then raised to 165℃ and reacted for 2 hours, followed by a reaction at 190℃ for 3 hours. The temperature was then raised to 205℃ and reacted until the acid value dropped to 5 mg KOH / g. The temperature was then raised to 230℃ and gradually reduced to 1.0 kPa for 2 hours. When the acid value dropped to 1.5 mg KOH / g, heating was stopped. After the reaction system cooled down, the product was discharged and placed in a vacuum drying oven and dried at 100℃ for 8 hours to obtain an aromatic modified copolysaturated polyester.

[0061] S4. Prepare aging-resistant building wires with low conductivity loss.

[0062] Weigh out 4 parts by weight of epoxidized soybean oil, 1 part of antioxidant 1010 and 0.8 parts of calcium stearate, mix them evenly to obtain the auxiliary additive;

[0063] Weigh out 100 parts by weight of polyvinyl chloride, 1.5 parts by weight of polyethylene grafted glycidyl methacrylate, 0.15 parts by weight of chlorinated polyethylene, and 5.8 parts by weight of auxiliary additives and add them to a high-speed mixer. Mix at 1000 rpm for 5 minutes. Then add 6 parts by weight of polymethylsiloxane-coated polyimide aerogel, 5 parts by weight of fluorine-modified copolymer polysiloxane, and 12 parts by weight of aromatic-modified copolymer saturated polyester. Continue mixing for 8 minutes and then transfer to a twin-screw extruder. The twin-screw extruder has 6 temperature zones set from the feed end to the die head, with temperatures of 185℃, 190℃, 195℃, 195℃, 190℃, and 190℃ respectively. The spindle speed is 40 rpm. After melting, the extruded material is coated onto the outside of the copper wire conductive core. After coating, the material is initially cooled with 60℃ warm water, then cooled and shaped with 25℃ cold water, and then dried with hot air. After cooling, a low-conductivity, aging-resistant fabric wire is obtained.

[0064] Example 3

[0065] This embodiment provides a method for preparing a low-conductivity, aging-resistant electrical wire, including the following steps:

[0066] S1. Preparation of polymethylsiloxane-coated polyimide aerogel

[0067] Weigh 100g of 4,4'-diaminodiphenyl ether and add it to a reaction vessel containing 2650mL of N-methylpyrrolidone. Stir until completely dissolved, then add 225g of hexafluorodianhydride and stir for 50min. Next, add 250mL of 0.87wt% N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene and stir for 8min. Then, add 522mL of propionic anhydride and 325mL of pyridine and stir for 15min. Pour the mixture into a mold, seal it, and let it stand until gelled. Seal it with anhydrous ethanol and age it at 75℃ for 3 days. Then, perform three solvent replacements with anhydrous ethanol. Transfer the gel to a supercritical carbon dioxide drying vessel, heat it to 55℃, pressurize it to 13MPa, and dry it for about 8h. After cooling to room temperature, remove it, pulverize it, and pass it through a 500-mesh sieve to obtain a polyimide aerogel matrix.

[0068] Weigh out 132g of methyltrimethoxysilane, 100g of urea, 0.2mL of acetic acid and 6g of hexadecyltrimethylammonium bromide and add them to a reactor containing 600mL of deionized water. After stirring for 50min, add 25g of polyimide aerogel matrix and impregnate at 55℃ for 22h. After solvent replacement with anhydrous ethanol three times, transfer the gel to a supercritical carbon dioxide drying reactor, heat to 55℃ and pressurize to 13MPa to dry for about 8h. After cooling to room temperature, remove the gel, pulverize it and pass it through a 500-mesh sieve to obtain polymethylsiloxane-coated polyimide aerogel.

[0069] S2, Preparation of fluorine-modified copolysiloxane

[0070] Under a nitrogen atmosphere, 100g of trifluoropropylmethylcyclotrisiloxane and 900g of octamethylcyclotetrasiloxane were weighed and added to a reaction vessel. The mixture was stirred at 80°C for 25 min. Then, 14.5g of 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and 0.8g of tetramethylammonium hydroxide were added and the mixture was reacted at 100°C for 6 h. The temperature was then raised to 145°C and reacted for 50 min. The temperature was then raised to 170°C and stirred for 1.5 h under a vacuum of 0.8 kPa. After the reaction was completed, the heating was stopped and the mixture was cooled to 25°C. Ethyl acetate was added and stirred until completely dissolved. Then, 4 volumes of anhydrous methanol were added and stirred for 8 min. The mixture was allowed to stand for 15 min, and the mixture was separated. The lower oily layer was collected, washed three times with anhydrous methanol, and then transferred to a vacuum drying oven and dried at 55°C for 7 h to obtain fluorine-modified copolysiloxane.

[0071] S3. Preparation of aromatic-modified copolysaturated polyester

[0072] Under a nitrogen atmosphere, 550g of 1,4-cyclohexanediethanol, 450g of 1,6-hexanediol, the amount of phthalic anhydride to be added calculated as 0.52 times the total molar amount of hydroxyl groups in 1,4-cyclohexanediethanol and 1,6-hexanediol, and 0.43g of tetrabutyl titanate were weighed and added to a reactor. The mixture was heated to 140℃ and stirred for 50 min to melt and mix the raw materials. The temperature was then raised to 160℃ and reacted for 1.5 h, followed by 185℃ and 2.5 h. The temperature was then raised to 200℃ and reacted until the acid value dropped to 4.5 mg KOH / g. The temperature was then raised to 220℃ and gradually reduced to 0.8 kPa and reacted for 1.5 h. When the acid value dropped to 1.2 mg KOH / g, heating was stopped. After the reaction system cooled down, the product was discharged and placed in a vacuum drying oven and dried at 90℃ for 7 h to obtain an aromatic modified copolysaturated polyester.

[0073] S4. Prepare aging-resistant building wires with low conductivity loss.

[0074] Weigh out 3.5 parts of epoxidized soybean oil, 0.8 parts of antioxidant 1010 and 0.7 parts of calcium stearate by weight, mix them evenly to obtain the auxiliary additive;

[0075] Weigh out 100 parts by weight of polyvinyl chloride, 1.2 parts by weight of polyethylene grafted glycidyl methacrylate, 0.1 parts by weight of chlorinated polyethylene, and 5 parts by weight of auxiliary additives. Add them to a high-speed mixer and mix at 900 rpm for 4 minutes. Then add 5 parts by weight of polymethylsiloxane-coated polyimide aerogel, 4.5 parts by weight of fluorine-modified copolymer polysiloxane, and 10 parts by weight of aromatic-modified copolymer saturated polyester. Continue mixing for 6 minutes and then transfer to a twin-screw extruder. The twin-screw extruder has 6 temperature zones set from the feed end to the die head, with temperatures of 185℃, 190℃, 195℃, 195℃, 190℃, and 190℃ respectively. The spindle speed is 35 rpm. After melting, the extruded material is coated onto the outside of the copper wire conductive core. After coating, the material is initially cooled with 55℃ warm water, then cooled and shaped with 20℃ cold water, and then dried with hot air. After cooling, a low-conductivity, aging-resistant fabric wire is obtained.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 3 is that the polyimide aerogel matrix in step S1 is used instead of the polymethylsiloxane-coated polyimide aerogel in step S4.

[0078] Comparative Example 2

[0079] The difference between this comparative example and Example 3 is that step S1 is omitted, and polymethylsiloxane-coated polyimide aerogel is not added in step S4.

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 3 is that step S2 is omitted and fluorine-modified copolysiloxane is not added in step S4.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 3 is that step S3 is omitted, and aromatic modified copolysaturated polyester is not added in step S4.

[0084] Performance testing:

[0085] Referring to standard GB / T 31838.8-2024 "Dielectric and resistive properties of solid insulating materials - Part 8: Determination of dielectric properties (AC method) - Relative permittivity and dielectric loss factor (frequency 1 MHz~300 MHz)", the dielectric loss factor of the low conductivity loss aging-resistant building wire outer sheath prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0086] Referring to standard GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods for Thickness and Dimensional Measurement and Mechanical Properties", the tensile stress and elongation at break of the outer sheath of the low conductivity loss aging-resistant building wires prepared in Examples 1-3 and Comparative Examples 1-4 were tested.

[0087] Referring to standard GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods - Thermal Aging Test Method", the low conductivity loss resistant aging-resistant outer sheaths of electrical wires prepared in Examples 1-3 and Comparative Examples 1-4 were pretreated by placing them for 16 hours after the finished electrical wire sheaths were formed. Then, the samples were vertically suspended inside a forced-ventilation thermal aging oven with a spacing of not less than 20 mm between the samples. The oven temperature was set at 100±2℃, and thermal aging was carried out for 168 hours. After aging, the samples were removed, protected from direct sunlight, and allowed to stand at room temperature for at least 16 hours. The dielectric loss factor, tensile stress, and elongation at break of the aged samples were then tested. The specific test results are shown in Table 1 below.

[0088] Table 1 - Basic Performance Test Data of the Samples

[0089]

[0090] Data Analysis:

[0091] Comparative analysis of the data in Table 1 shows that the low conductivity loss and aging-resistant building wire prepared by this invention has the following characteristics: before thermal aging, the dielectric loss factor of its outer sheath is 0.0015, the tensile stress is 23.8 MPa, and the elongation at break is 372%; after thermal aging, the dielectric loss factor of its outer sheath is 0.0022, the tensile stress is 21.9 MPa, and the elongation at break is 286%.

[0092] Comparative Example 1 used a bare polyimide aerogel without a polymethylsiloxane outer layer. The polar imide groups of the aerogel were in direct contact with the PVC matrix, resulting in numerous micro-voids at the interface and significantly increased interfacial polarization. This led to a dielectric loss factor of 0.0038 before thermal aging. Simultaneously, the bare aerogel had extremely poor compatibility with PVC, easily causing stress concentration under stress. Before thermal aging, the tensile stress was only 18.1 MPa and the elongation at break was only 212%. During high-temperature aging, oxygen and water vapor directly invaded the aerogel skeleton, causing oxidative deterioration and the generation of a large number of polar degradation products. After thermal aging, the dielectric loss factor surged to 0.0062, the tensile stress dropped to 14.5 MPa, and the elongation at break was only 130%.

[0093] Comparative Example 2, lacking a porous, low-dielectric siloxane-coated aerogel as a low-loss framework, resulted in a large number of unbound polar groups in the PVC matrix, leading to severe dipole polarization under alternating electric fields. Before thermal aging, the dielectric loss factor reached 0.0065. Simultaneously, the absence of rigid nano-reinforcing units reduced stress dispersion capabilities, resulting in a tensile stress of 19.5 MPa and an elongation at break of 244% before thermal aging. Under long-term thermo-oxidative conditions, the absence of a siloxane barrier layer to prevent the dechlorination reaction of PVC led to the continuous generation of numerous polar byproducts. After thermal aging, the dielectric loss factor increased to 0.0105, while the tensile stress and elongation at break decreased to 15.8 MPa and 152%, respectively.

[0094] Comparative Example 3, lacking a fluorosilicone component with low-polarity CF bonds, could not fix the molecular dipoles or form an inert protective film on the sheath surface, resulting in increased polarization of the matrix molecules and a dielectric loss factor of 0.0032 before thermal aging. Simultaneously, the absence of a flexible fluorosilicone segment toughening structure reduced the material's ductility, with an elongation at break of only 273% before thermal aging. During the thermal aging stage, the lack of CF bonds to resist thermal and oxygen erosion made PVC more prone to decomposition and the generation of polar groups. After thermal aging, the dielectric loss factor increased to 0.0053, the tensile stress decreased to 17.8 MPa, and the elongation at break decreased to 187%.

[0095] Comparative Example 4, lacking a compatible bridge of aromatic polyester with carboxyl groups at both ends, prevented the polysiloxane filler from forming hydrogen bonds with the PVC matrix, resulting in severe phase separation, numerous interfacial defects, and a sharp increase in interfacial polarization. Before thermal aging, the dielectric loss factor reached 0.0042. The phase-separated structure was prone to microcracks, leading to a significant decrease in material strength and toughness. Before thermal aging, the tensile stress was only 17.7 MPa, and the elongation at break was only 181%. During thermal aging, the gaps between the two phases accelerated the penetration of oxygen and heat, causing simultaneous degradation of PVC and silicon filler. After thermal aging, the dielectric loss factor rose to 0.0075, the tensile stress was only 13.2 MPa, and the elongation at break was as low as 107%.

[0096] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-conductivity-loss, aging-resistant fabric wire, characterized in that, Includes a conductive core and an outer sheath layer; The outer sheath layer comprises the following components by weight: 100 parts polyvinyl chloride, 4-6 parts polymethylsiloxane-coated polyimide aerogel, 4-5 parts fluorine-modified copolymer polysiloxane, 8-12 parts aromatic-modified copolymer saturated polyester, 0.8-1.5 parts polyethylene grafted glycidyl methacrylate, 0.05-0.15 parts chlorinated polyethylene, and 4.1-5.8 parts auxiliary additives; The polymethylsiloxane-coated polyimide aerogel is prepared by polycondensation, crosslinking and imidization of 4,4′-diaminodiphenyl ether and 1,3,5-tris(4-aminophenoxy)benzene with hexafluorodianhydride to form a polyimide aerogel matrix, which is then coated in situ by hydrolysis and condensation of methyltrimethoxysilane.

2. The low conductivity loss and aging-resistant building wire according to claim 1, characterized in that, The polymethylsiloxane-coated polyimide aerogel was prepared by the following steps: A1. Add 4,4'-diaminodiphenyl ether to a reaction vessel containing N-methylpyrrolidone and stir until completely dissolved. Then add hexafluorodianhydride and stir for 40-60 min. Next, add a solution of 1,3,5-tris(4-aminophenoxy)benzene in N-methylpyrrolidone and stir for 5-10 min. Then add propionic anhydride and pyridine and stir for 10-20 min. After post-treatment, a polyimide aerogel matrix is ​​obtained. A2. Add methyltrimethoxysilane, urea, acetic acid and hexadecyltrimethylammonium bromide to a reactor containing deionized water, stir for 40-60 min, then add polyimide aerogel matrix, impregnate at 50-60℃ for 20-24 h, and then perform post-treatment to obtain polymethylsiloxane-coated polyimide aerogel.

3. The low conductivity loss and aging-resistant fabric wire according to claim 2, characterized in that, In step A1, the ratio of the amounts of 4,4'-diaminodiphenyl ether, N-methylpyrrolidone, hexafluorodianhydride, the N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene, propionic anhydride, and pyridine is 2g:50-55mL:4.5g:5mL:10.4-10.5mL:6.5mL, wherein the mass fraction of the N-methylpyrrolidone solution of 1,3,5-tris(4-aminophenoxy)benzene is 0.87%; in step A2, the ratio of the amounts of methyltrimethoxysilane, urea, acetic acid, hexadecyltrimethylammonium bromide, deionized water, and polyimide aerogel matrix is ​​13.0-13.3g:10g:0.02mL:0.6g:60mL:2.5g.

4. The low conductivity loss and aging-resistant fabric wire according to claim 1, characterized in that, The preparation method of the fluorine-modified copolysiloxane is as follows: under a nitrogen atmosphere, trifluoropropylmethylcyclotrisiloxane and octamethylcyclotetrasiloxane are added to a reaction vessel and stirred at 70-90℃ for 20-30 min. Then, 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide are added and reacted at 90-110℃ for 5-6 h. Then, the temperature is raised to 140-150℃ and reacted for 40-60 min. Then, the temperature is raised to 160-180℃ and stirred for 1-2 h under a vacuum of 0.5-1 kPa. After post-treatment, the fluorine-modified copolysiloxane is obtained.

5. The low conductivity loss and aging-resistant fabric wire according to claim 4, characterized in that, The ratio of trifluoropropylmethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3-bis(3-chloropropyl)-,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide is 10g:90g:1.43-1.47g:0.08g.

6. The low conductivity loss and aging-resistant building wire according to claim 1, characterized in that, The method for preparing the aromatic modified copolysaturated polyester is as follows: Under a nitrogen atmosphere, phthalic anhydride, 1,4-cyclohexanediol, 1,6-hexanediol and tetrabutyl titanate are added to a reaction vessel, heated to 130-140℃ and stirred for 40-60 minutes to melt and mix the raw materials. Then, the temperature is raised to 150-165℃ and reacted for 1-2 hours. Subsequently, the temperature is raised to 180-190℃ and reacted for 2-3 hours. Then, the temperature is raised to 195-205℃ and reacted until the acid value drops to 4-5 mg KOH / g. The temperature is raised to 210-230℃, and the pressure is gradually reduced to 0.5-1.0 kPa and reacted for 1-2 hours. When the acid value drops to 1.0-1.5 mg KOH / g, heating is stopped. After the reaction system cools down, the product is discharged and placed in a vacuum drying oven and dried at 80-100℃ for 6-8 hours to obtain the aromatic modified copolysaturated polyester.

7. The low conductivity loss and aging-resistant fabric wire according to claim 6, characterized in that, The ratio of 1,4-cyclohexanediethanol, 1,6-hexanediol and tetrabutyl titanate is 55g:45g:0.043g, and the amount of phthalic anhydride added is 0.52 times the total molar amount of hydroxyl groups in 1,4-cyclohexanediethanol and 1,6-hexanediol.

8. The low conductivity loss and aging-resistant building wire according to claim 1, characterized in that, The preparation method of the low conductivity loss aging-resistant fabric wire is as follows: Polyvinyl chloride, polyethylene grafted with glycidyl methacrylate, chlorinated polyethylene and auxiliary additives are added to a high-speed mixer and mixed at a speed of 800-1000 r / min for 3-5 min. Then, polymethylsiloxane-coated polyimide aerogel, fluorine-modified copolymer polysiloxane and aromatic-modified copolymer saturated polyester are added and mixed for another 5-8 min. The mixture is then transferred to a twin-screw extruder, melted and extruded to coat the outside of the conductive core. After coating, the wire is initially cooled with warm water at 50-60℃, then cooled and shaped with cold water at 20-25℃, and then dried with hot air. After cooling, the low conductivity loss aging-resistant fabric wire is obtained.

9. The low conductivity loss and aging-resistant fabric wire according to claim 8, characterized in that, The conductive core is made of copper wire; the temperature of the six temperature zones of the twin-screw extruder, set from the feed end toward the die head, is 185℃, 190℃, 195℃, 195℃, 190℃, and 190℃ respectively; the spindle speed of the twin-screw extruder is 30-40 r / min.

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