An anti-aging cable and its preparation method

Abstract

This invention belongs to the field of cable material technology, specifically relating to an anti-aging cable and its preparation method. The anti-aging cable of this invention comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 90-100 parts PVC resin, 15-20 parts linear low-density polyethylene, 10-15 parts ethylene-octene copolymer, 12-18 parts plasticizer, 5-8 parts anti-aging agent, 3-5 parts calcium-zinc stabilizer, 3-5 parts modified carbon nanotubes, and 2-3 parts lubricant. The anti-aging agent prepared by this invention through molecular structure design not only significantly improves the anti-aging performance of the cable sheath material but also effectively enhances its flame-retardant properties. Furthermore, the modified carbon nanotubes obtained by this invention significantly improve the mechanical properties and water resistance of the cable sheath material.

Description

Technical Field

[0001] This invention belongs to the field of cable material technology, specifically relating to an anti-aging cable and its preparation method. Background Technology

[0002] With the rapid development of industries such as power and communications, the performance requirements for cables, as a key basic material, are increasingly stringent, especially regarding long-term stability in harsh environments such as outdoor conditions, high temperatures, and high humidity. The cable sheath, as the first line of defense protecting the internal structure, needs to possess excellent anti-aging, weather resistance, mechanical properties, and flame retardancy. However, traditional cable sheath materials (such as PVC and polyethylene) are susceptible to the effects of ultraviolet radiation, oxygen, moisture, and metal ions during long-term use, leading to thermo-oxidative aging, photo-oxidative degradation, and metal-catalyzed oxidation. This results in problems such as decreased mechanical properties, cracking, and brittleness, severely impacting the cable's service life and safety.

[0003] Currently, the main methods to improve the anti-aging performance of cable sheaths are the addition of antioxidants and light stabilizers. Traditional antioxidants, such as hindered phenols and phosphites, can delay the thermo-oxidative aging of materials to some extent, but their simple molecular structure limits their free radical capture efficiency and they cannot simultaneously provide UV shielding and flame retardant properties. Light stabilizers, such as UV absorbers and hindered amines, can absorb UV rays, but their synergistic effect with antioxidants is usually weak. Furthermore, while existing flame retardants can improve the flame retardancy of materials, they negatively impact the mechanical properties and environmental friendliness of the materials. Therefore, there is an urgent need to develop a new type of anti-aging cable sheath material that, through molecular structure design and nanotechnology modification, synergistically improves the material's anti-aging properties, mechanical properties, and environmental adaptability to meet the long-term stable use requirements of cables under complex operating conditions. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the primary objective of this invention is to provide an anti-aging cable. The anti-aging agent prepared through molecular structure design in this invention not only significantly improves the anti-aging performance of cable sheath materials but also effectively enhances their flame-retardant properties. Furthermore, the modified carbon nanotubes obtained by this invention can significantly improve the mechanical properties and water resistance of cable sheath materials.

[0005] Another objective of this invention is to provide a method for preparing anti-aging cables, which is simple to operate and easy to mass-produce.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An anti-aging cable comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 90-100 parts of PVC resin, 15-20 parts of linear low-density polyethylene, 10-15 parts of ethylene-octene copolymer, 12-18 parts of plasticizer, 5-8 parts of anti-aging agent, 3-5 parts of calcium-zinc stabilizer, 3-5 parts of modified carbon nanotubes, and 2-3 parts of lubricant.

[0008] The anti-aging agent is prepared by the following process:

[0009] (1) 1,2,4,5-Tetraazine-3,6-diamine was added to methanol, and then a methanol solution of 3,5-di-tert-butyl-4-hydroxybenzaldehyde was added to react. After the reaction was completed, the mixture was concentrated under reduced pressure and separated to obtain compound 1.

[0010] (2) Compound 1 was added to methanol, and a methanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added to react. After the reaction was completed, the reaction solution was concentrated, filtered, washed and dried to obtain the anti-aging agent.

[0011] Further, in step (1), the molar ratio of 1,2,4,5-tetraazine-3,6-diamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde is 1:(2-2.2); the ratio of the amount of 1,2,4,5-tetraazine-3,6-diamine to methanol is 1 mmol:2-3 mL; the concentration of the methanol solution of 3,5-di-tert-butyl-4-hydroxybenzaldehyde is 1.1-1.5 mol / L; the reaction temperature is 50-60℃ and the reaction time is 0.5-1 h.

[0012] Further, in step (2), the molar ratio of compound 1 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(2-2.2); the ratio of compound 1 to methanol is 1 mmol:2-3 mL; the concentration of the methanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1.1-2 mol / L; the reaction temperature is 70-80℃ and the reaction time is 6-7 h.

[0013] Furthermore, the modified carbon nanotubes are prepared by the following process:

[0014] a. Carboxylated multi-walled carbon nanotubes were added to anhydrous ethanol, and then dicyclohexylcarbodiimide was added to obtain a dispersion; anhydrous ethanol solution of 4-aminobenzenesulfonic acid was added to the dispersion and stirred to react; the mixture was filtered, washed, and dried to obtain sulfonated carbon nanotubes.

[0015] b. Sulfonated carbon nanotubes were added to anhydrous ethanol A to obtain a dispersion of sulfonated carbon nanotubes; hexadecyltrimethoxysilane was added to anhydrous ethanol B, then water was added and stirred until well mixed, and then added to the dispersion of sulfonated carbon nanotubes and stirred to react; centrifugation, washing, and drying were performed to obtain modified carbon nanotubes.

[0016] Further, in step a, the ratio of carboxylated multi-walled carbon nanotubes, dicyclohexylcarbodiimide, and anhydrous ethanol is 1 g: 1.5-2.0 g: 200-250 mL; the volume ratio of the dispersion to the anhydrous ethanol solution of 4-aminobenzenesulfonic acid is 1: (1-1.3), and the ratio of 4-aminobenzenesulfonic acid to anhydrous ethanol in the anhydrous ethanol solution of 4-aminobenzenesulfonic acid is 1-2 g: 200-250 mL; the temperature of the stirring reaction is 50-60℃, and the time is 12-15 h.

[0017] Further, in step b, the ratio of sulfonated carbon nanotubes to anhydrous ethanol A is 1 g: 200-250 mL; the ratio of sulfonated carbon nanotubes, hexadecyltrimethoxysilane, anhydrous ethanol B, and water is 1 g: 0.5-0.7 g: 50 mL: 2 mL; the stirring reaction temperature is 50-60℃, and the time is 4-6 h.

[0018] Furthermore, the plasticizer is dioctyl phthalate; the lubricant is zinc stearate; and the calcium-zinc stabilizer is CZ-106-2.

[0019] The present invention also provides a method for preparing the anti-aging cable, comprising the following steps:

[0020] S1. Mix PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer at 80-90℃ for 10-12 minutes, continue heating to 110-130℃, add a mixture of plasticizer, anti-aging agent, modified carbon nanotubes, and lubricant, and knead for 5-8 minutes to obtain sheath material.

[0021] S2. An insulating layer is applied to the surface of the conductor to obtain a conductor with an insulating layer.

[0022] S3. The sheath material obtained in step S1 is extruded through a twin-screw extruder to coat the surface of the insulation layer, forming a sheath layer, and thus obtaining the anti-aging cable.

[0023] Furthermore, the extrusion temperature of the twin-screw extruder is 150-190℃.

[0024] The present invention has the following advantages over the prior art:

[0025] 1. The anti-aging agent prepared by this invention through molecular structure design not only significantly improves the anti-aging performance of cable sheath materials but also effectively enhances their flame retardant properties. The synergistic effect of the hindered phenolic structure and the 1,2,4,5-tetraazine ring structure in the anti-aging agent molecule can efficiently capture free radicals such as ·OH and ·OOH, delaying the thermo-oxidative aging of the material. The tetraazine ring structure and hindered amine in the molecule have broad ultraviolet absorption capabilities, effectively shielding ultraviolet rays and reducing photo-oxidative degradation. Furthermore, the nitrogen atom of the tetraazine ring can chelate with copper ions in the cable, inhibiting metal catalytic oxidation and further extending the material's service life. Meanwhile, the phosphorus-phenanthroline structure of DOPO decomposes at high temperatures, releasing PO· free radicals to exert a gas-phase flame retardant effect, while simultaneously promoting char formation, forming a dense phosphoric acid-nitrogen-containing carbon layer that isolates heat and oxygen, endowing the material with excellent flame retardant properties.

[0026] In addition, the amino groups in the anti-aging agent molecule can improve the compatibility with the PVC matrix through hydrogen bonding, promote the uniform dispersion of the anti-aging agent, and enable DOPO to be stably embedded in the material network. This avoids the problem of mechanical property degradation caused by migration of pure DOPO. Moreover, the conjugated system formed by the tetrazine ring and the phosphenanthrene structure of DOPO can improve molecular rigidity, reduce chain segment movement, and further enhance the mechanical strength of the material.

[0027] 2. This invention prepares sulfonated carbon nanotubes by amidation reaction of carboxylated multi-walled carbon nanotubes with 4-aminobenzenesulfonic acid, and then modifies their surface with hexadecyltrimethoxysilane (HDTMS). The resulting modified carbon nanotubes significantly improve the mechanical properties and water resistance of cable sheath materials. Specifically, the hydrolysis of the siloxane groups in HDTMS forms stable Si-OS covalent bonds with the sulfonic acid groups on the surface of the sulfonated carbon nanotubes. Combined with the steric hindrance of the long-chain alkyl groups, this effectively improves the dispersion stability of the carbon nanotubes. Simultaneously, the molecular chain entanglement between the long-chain alkyl groups and the PVC resin matrix, as well as the hydrogen bonding interaction between the sulfonic acid groups and the resin, not only further improve the interfacial compatibility of the carbon nanotubes but also effectively improve stress transfer efficiency, enhancing the strength and toughness of the material. Furthermore, the hydrophobic long-chain alkyl groups of HDTMS form a low surface energy protective layer on the surface of the sulfonated carbon nanotubes, improving the material's water resistance. Attached Figure Description

[0028] Figure 1 The image shows the infrared spectrum of the modified carbon nanotubes obtained in Example 1 of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.

[0030] The PVC resin of this invention is SG-3 type resin; the linear low-density polyethylene is model DFDA6101; the ethylene-octene copolymer is model 8180; the carboxylated multi-walled carbon nanotubes have an inner diameter of 5-12 nm, an outer diameter of 30-50 nm, a length of 10-20 µm, and -COOH > 2 wt%.

[0031] Example 1

[0032] An anti-aging cable comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 95 parts PVC resin, 18 parts linear low-density polyethylene, 12 parts ethylene-octene copolymer, 15 parts plasticizer (dioctyl phthalate), 7 parts anti-aging agent, 4 parts calcium-zinc stabilizer (CZ-106-2), 4 parts modified carbon nanotubes, and 2.5 parts lubricant (zinc stearate).

[0033] The anti-aging agent is prepared by the following process:

[0034]

[0035] (1) 1,2,4,5-Tetraazine-3,6-diamine and methanol were added to methanol at a ratio of 1 mmol: 2.5 mL. A methanol solution of 3,5-di-tert-butyl-4-hydroxybenzaldehyde with a concentration of 1.3 mol / L was slowly added dropwise at 55 °C with stirring. The molar ratio of 1,2,4,5-tetraazine-3,6-diamine to 3,5-di-tert-butyl-4-hydroxybenzaldehyde was 1:2.1. After the addition was complete, the reaction continued for 0.75 h. After the reaction was completed, the methanol and water were removed by vacuum concentration, and the mixture was separated by silica gel column chromatography (petroleum ether / ethyl acetate = 20 / 80) to obtain compound 1. ¹H NMR (C 33 H 44 N6O2, 400 MHz, d6-DMSO) δ: 9.21 (s, 2H), 7.51 (s, 4H), 7.42(s, 2H), 1.45 (s, 36H); HRMS (ESI+): [M+H] + The calculation yields 545.35, and the value is found to be 545.35.

[0036] (2) Compound 1 was added to methanol at a ratio of 1 mmol: 2.5 mL; a methanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with a concentration of 1.5 mol / L was slowly added at 75°C with stirring. The molar ratio of compound 1 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:2.1; after the addition was complete, the reaction continued for 6.5 h; after the reaction was completed, the reaction solution was concentrated to 1 / 3 of its original volume, and the solid was precipitated by adding ice water. The solid was filtered, washed with water, and dried to obtain the anti-aging agent; 1H NMR (C 56 H 62 N6O6P2, 400 MHz, d6-DMSO) δ: 8.02-7.98 (m, 2H), 7.77-7.73 (m, 2H), 7.50-7.38 (m, 10H), 7.30-7.27(m, 2H), 6.97 (s, 4H), 6.79(s, 2H), 6.72(s, 2H), 4.01(d, 2H), 1.38 (s, 36H);HRMS (ESI+): [M+H] + The calculation yields 977.42, and the value is found to be 977.42.

[0037] The modified carbon nanotubes are prepared by the following process:

[0038] a. Carboxylated multi-walled carbon nanotubes were added to anhydrous ethanol, followed by dicyclohexylcarbodiimide. The ratio of carboxylated multi-walled carbon nanotubes, dicyclohexylcarbodiimide, and anhydrous ethanol was 1 g: 1.8 g: 230 mL. The mixture was sonicated for 35 min to obtain a dispersion. The dispersion was then mixed with an anhydrous ethanol solution of 4-aminobenzenesulfonic acid (the ratio of 4-aminobenzenesulfonic acid to anhydrous ethanol was 1.5 g: 230 mL). The volume ratio of the dispersion to the anhydrous ethanol solution of 4-aminobenzenesulfonic acid was 1:1.2. The mixture was stirred at 55 °C for 13 h. The mixture was filtered, and the collected crude product was washed successively with anhydrous ethanol and deionized water until the pH of the washing filtrate was close to 7. Finally, the product was dried under vacuum to obtain sulfonated carbon nanotubes.

[0039] b. Sulfonated carbon nanotubes were added to anhydrous ethanol A at a ratio of 1 g: 230 mL, and the mixture was sonicated for 35 min to obtain a dispersion of sulfonated carbon nanotubes. Hexadecyltrimethoxysilane was added to anhydrous ethanol B, and deionized water was added dropwise and stirred at room temperature for 35 min before being slowly added to the dispersion of sulfonated carbon nanotubes. The ratio of sulfonated carbon nanotubes, hexadecyltrimethoxysilane, anhydrous ethanol B, and deionized water was 1 g: 0.6 g: 50 mL: 2 mL. The mixture was stirred at 55 °C for 5 h. After centrifugation, the collected solid was washed twice with ethanol / water (v / v = 1 / 1) and finally dried under vacuum to obtain modified carbon nanotubes.

[0040] The infrared spectrum of modified carbon nanotubes is as follows: Figure 1 As shown. Compared to carboxylated multi-walled carbon nanotubes, the curve for sulfonated carbon nanotubes shows a higher 1630 cm⁻¹. -1 A strong tensile vibration peak of amide C=O appears at 1574 cm⁻¹. -1 and 3326cm -1 The characteristic peak of the amide NH vibration appears at 1240 cm⁻¹. -1 and 1307cm -1 The presence of characteristic peaks for sulfonate groups at approximately 2925 cm⁻¹ indicates the successful synthesis of sulfonated carbon nanotubes. Compared to sulfonated multi-walled carbon nanotubes, the modified carbon nanotubes exhibit a higher peak at approximately 2925 cm⁻¹. -1 2854cm -1 The characteristic peak at 1467 cm⁻¹ is enhanced. -1 The characteristic peak of CO appeared at 1240 cm⁻¹. -1 and 1307cm -1 The peak at 3400 cm⁻¹ weakens, and unreacted silanol groups further weaken the peak at 3400 cm⁻¹. -1 The peak at the point broadens, indicating that the long-chain hydrophobic alkyl grafting of hexadecyltrimethoxysilane was successful.

[0041] This embodiment also provides a method for preparing an anti-aging cable, including the following steps:

[0042] S1. Mix PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer at 85°C for 11 min, continue heating to 120°C, add a mixture of plasticizer, anti-aging agent, modified carbon nanotubes, and lubricant, and knead for 7 min to obtain sheath material.

[0043] S2. An insulating layer is applied to the surface of the conductor to obtain a conductor with an insulating layer.

[0044] S3. The sheath material obtained in step S1 is extruded through a twin-screw extruder at an extrusion temperature of 180°C; the sheath material is then coated onto the surface of the insulation layer to form a sheath layer, thus obtaining an anti-aging cable.

[0045] Example 2

[0046] An anti-aging cable comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 90 parts PVC resin, 15 parts linear low-density polyethylene, 10 parts ethylene-octene copolymer, 12 parts plasticizer (dioctyl phthalate), 5 parts anti-aging agent, 3 parts calcium-zinc stabilizer (CZ-106-2), 3 parts modified carbon nanotubes, and 2 parts lubricant (zinc stearate).

[0047] The anti-aging agent is prepared by the following process:

[0048] (1) 1,2,4,5-Tetraazine-3,6-diamine and methanol were added to methanol at a ratio of 1 mmol: 2 mL. A methanol solution of 3,5-di-tert-butyl-4-hydroxybenzaldehyde with a concentration of 1.1 mol / L was slowly added dropwise at 50 °C with stirring. The molar ratio of 1,2,4,5-tetraazine-3,6-diamine to 3,5-di-tert-butyl-4-hydroxybenzaldehyde was 1:2. After the addition was complete, the reaction was continued for 0.5 h. After the reaction was completed, the methanol and water were removed by vacuum concentration and separated by silica gel column chromatography (petroleum ether / ethyl acetate = 20 / 80) to obtain compound 1. The 1H NMR and HRMS (ESI+) results of compound 1 were the same as those in Example 1.

[0049] (2) Compound 1 was added to methanol at a ratio of 1 mmol to 2 mL. A methanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with a concentration of 1.1 mol / L was slowly added at 70°C with stirring. The molar ratio of compound 1 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:2. After the addition was complete, the reaction was continued for 6 h. After the reaction was completed, the reaction solution was concentrated to 1 / 3 of the original volume, and the solid was precipitated by adding ice water. The solid was filtered, washed with water, and dried to obtain the anti-aging agent. The 1H NMR and HRMS (ESI+) results of the anti-aging agent were the same as those in Example 1.

[0050] The modified carbon nanotubes are prepared by the following process:

[0051] a. Carboxylated multi-walled carbon nanotubes were added to anhydrous ethanol, followed by dicyclohexylcarbodiimide. The ratio of carboxylated multi-walled carbon nanotubes, dicyclohexylcarbodiimide, and anhydrous ethanol was 1 g: 1.5 g: 200 mL. The mixture was sonicated for 30 min to obtain a dispersion. The dispersion was then mixed with an anhydrous ethanol solution of 4-aminobenzenesulfonic acid (the ratio of 4-aminobenzenesulfonic acid to anhydrous ethanol was 1 g: 200 mL), with a volume ratio of 1:1. The mixture was stirred at 50 °C for 15 h. The mixture was filtered, and the collected crude product was washed sequentially with anhydrous ethanol and deionized water until the pH of the washing filtrate was close to 7. Finally, the product was vacuum dried to obtain sulfonated carbon nanotubes.

[0052] b. Sulfonated carbon nanotubes were added to anhydrous ethanol A at a ratio of 1 g: 200 mL, and the mixture was sonicated for 30 min to obtain a dispersion of sulfonated carbon nanotubes. Hexadecyltrimethoxysilane was added to anhydrous ethanol B, and deionized water was added dropwise and stirred at room temperature for 30 min before being slowly added to the dispersion of sulfonated carbon nanotubes. The ratio of sulfonated carbon nanotubes, hexadecyltrimethoxysilane, anhydrous ethanol B, and water was 1 g: 0.5 g: 50 mL: 2 mL. The mixture was stirred at 50 °C for 6 h. After centrifugation, the collected solid was washed twice with ethanol / water (v / v = 1 / 1) and finally dried under vacuum to obtain modified carbon nanotubes.

[0053] This embodiment also provides a method for preparing an anti-aging cable, including the following steps:

[0054] S1. Mix PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer at 80°C for 12 minutes, continue heating to 110°C, add a mixture of plasticizer, anti-aging agent, modified carbon nanotubes, and lubricant, and knead for 8 minutes to obtain sheath material.

[0055] S2. An insulating layer is applied to the surface of the conductor to obtain a conductor with an insulating layer.

[0056] S3. The sheath material obtained in step S1 is extruded through a twin-screw extruder at an extrusion temperature of 150°C; the sheath material is then coated onto the surface of the insulation layer to form a sheath layer, thus obtaining an anti-aging cable.

[0057] Example 3

[0058] An anti-aging cable comprises, from the inside out, a conductor, an insulation layer, and a sheath layer. The sheath layer comprises the following raw materials in parts by weight: 100 parts PVC resin, 20 parts linear low-density polyethylene, 15 parts ethylene-octene copolymer, 18 parts plasticizer (dioctyl phthalate), 8 parts anti-aging agent, 5 parts calcium-zinc stabilizer (CZ-106-2), 5 parts modified carbon nanotubes, and 3 parts lubricant (zinc stearate).

[0059] The anti-aging agent is prepared by the following process:

[0060] (1) 1,2,4,5-Tetraazine-3,6-diamine and methanol were added to methanol at a ratio of 1 mmol: 3 mL. A methanol solution of 3,5-di-tert-butyl-4-hydroxybenzaldehyde with a concentration of 1.5 mol / L was slowly added dropwise at 60 °C with stirring. The molar ratio of 1,2,4,5-tetraazine-3,6-diamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde was 1:2.2. After the addition was complete, the reaction was continued for 1 h. After the reaction was completed, the methanol and water were removed by vacuum concentration and separated by silica gel column chromatography (petroleum ether / ethyl acetate = 20 / 80) to obtain compound 1. The 1H NMR and HRMS (ESI+) results of compound 1 were the same as those in Example 1.

[0061] (2) Compound 1 was added to methanol at a ratio of 1 mmol to 3 mL. A methanol solution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with a concentration of 2 mol / L was slowly added at 80°C with stirring. The molar ratio of compound 1 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:2.2. After the addition was complete, the reaction was continued for 7 h. After the reaction was completed, the reaction solution was concentrated to 1 / 3 of the original volume, and the solid was precipitated by adding ice water. The solid was filtered, washed with water, and dried to obtain the anti-aging agent. The 1H NMR and HRMS (ESI+) results of the anti-aging agent were the same as those in Example 1.

[0062] The modified carbon nanotubes are prepared by the following process:

[0063] a. Carboxylated multi-walled carbon nanotubes were added to anhydrous ethanol, followed by dicyclohexylcarbodiimide. The ratio of carboxylated multi-walled carbon nanotubes, dicyclohexylcarbodiimide, and anhydrous ethanol was 1 g: 2.0 g: 250 mL. The mixture was sonicated for 40 min to obtain a dispersion. The dispersion was then mixed with an anhydrous ethanol solution of 4-aminobenzenesulfonic acid (the ratio of 4-aminobenzenesulfonic acid to anhydrous ethanol was 2 g: 250 mL), with a volume ratio of 1:1.3. The mixture was stirred at 60 °C for 12 h. The mixture was filtered, and the collected crude product was washed sequentially with anhydrous ethanol and deionized water until the pH of the washing filtrate was close to 7. Finally, the product was vacuum dried to obtain sulfonated carbon nanotubes.

[0064] b. Sulfonated carbon nanotubes were added to anhydrous ethanol A at a ratio of 1 g: 250 mL, and the mixture was sonicated for 40 min to obtain a dispersion of sulfonated carbon nanotubes. Hexadecyltrimethoxysilane was added to anhydrous ethanol B, and deionized water was added dropwise and stirred at room temperature for 40 min before being slowly added to the dispersion of sulfonated carbon nanotubes. The ratio of sulfonated carbon nanotubes, hexadecyltrimethoxysilane, anhydrous ethanol B, and water was 1 g: 0.7 g: 50 mL: 2 mL. The mixture was stirred at 60 °C for 4 h. After centrifugation, the collected solid was washed three times with ethanol / water (v / v = 1 / 1) and finally dried under vacuum to obtain modified carbon nanotubes.

[0065] This embodiment also provides a method for preparing an anti-aging cable, including the following steps:

[0066] S1. Mix PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer at 90°C for 10 min, continue heating to 130°C, add a mixture of plasticizer, anti-aging agent, modified carbon nanotubes, and lubricant, and knead for 5 min to obtain sheath material.

[0067] S2. An insulating layer is applied to the surface of the conductor to obtain a conductor with an insulating layer.

[0068] S3. The sheath material obtained in step S1 is extruded through a twin-screw extruder at an extrusion temperature of 190°C; the sheath material is then coated onto the surface of the insulation layer to form a sheath layer, thus obtaining an anti-aging cable.

[0069] Comparative Example 1

[0070] Comparative Example 1 is basically the same as Example 1, except that the anti-aging agent is replaced with 3,5-di-tert-butyl-4-hydroxybenzaldehyde.

[0071] Comparative Example 2

[0072] Comparative Example 2 is basically the same as Example 1, except that: Compound 1 obtained in step (1) of Example 1 is directly physically mixed with DOPO.

[0073] Comparative Example 3

[0074] Comparative Example 3 is basically the same as Example 1, except that the modified carbon nanotubes are replaced with carboxylated multi-walled carbon nanotubes.

[0075] Comparative Example 4

[0076] Comparative Example 4 is basically the same as Example 1, except that step a is omitted in the preparation of modified carbon nanotubes, and the sulfonated carbon nanotubes in step b are replaced with carboxylated multi-walled carbon nanotubes.

[0077] Test Example 1

[0078] (1) The tensile strength and elongation at break of the sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 of the present invention were tested in accordance with the standard GB / T 1040.1-2018.

[0079] (2) To verify the anti-aging properties of the samples, referring to the standard GB / T 2951.12-2008, the sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 were placed in an aging chamber, and the fluorescent lamp irradiation intensity was set to 75 W / m². 2 The ultraviolet radiation intensity is 60 W / m 2 The temperature inside the chamber was set to 60±2℃. After 720 hours, the material was taken out and tested again for tensile strength and elongation at break. The retention rate of tensile strength and elongation at break was calculated. The retention rate = initial test index / test index after aging × 100%. The specific test data are shown in Table 1.

[0080] Table 1

[0081]

[0082] As can be seen from Table 1, the tensile strength and elongation at break of Examples 1-3 are higher than those of Comparative Examples 1-4, indicating that the anti-aging agent and modified carbon nanotubes introduced in this invention have good compatibility with other matrix components, giving the material good mechanical properties and anti-aging ability. Comparative Example 1 replaced the anti-aging agent with 3,5-di-tert-butyl-4-hydroxybenzaldehyde; Comparative Example 2 directly mixed Compound 1 obtained in step (1) of Example 1 with DOPO. The mechanical properties of Comparative Examples 1 and 2 are worse than those of Examples 1-3. This is because the amino group introduced into the molecular structure of the anti-aging agent can improve the compatibility with the PVC matrix, promote the uniform dispersion of the anti-aging agent, and avoid the problem of DOPO migration leading to a decrease in mechanical properties; moreover, the tetrazine ring in the anti-aging agent and the phosphoranone structure of DOPO can improve molecular rigidity, reduce chain segment movement, and further enhance the mechanical strength of the material.

[0083] Comparative Example 3 replaced the modified carbon nanotubes with carbon nanotubes; in Comparative Example 4, step a was omitted during the preparation of modified carbon nanotubes, and the sulfonated carbon nanotubes in step b were replaced with carboxylated multi-walled carbon nanotubes. The mechanical properties of Comparative Examples 3 and 4 were worse than those of Example 1. This phenomenon may be because: after the hydrolysis of the siloxane groups of the modified carbon nanotubes, they form stable Si-OS covalent bonds with the sulfonic acid groups on the surface of the sulfonated carbon nanotubes, which can effectively improve the dispersion stability of the carbon nanotubes; at the same time, the molecular chain entanglement between the long-chain alkyl groups and the PVC resin matrix, as well as the hydrogen bonding interaction between the sulfonic acid groups and the resin, can not only further improve the interfacial compatibility of the carbon nanotubes, but also improve the strength and toughness of the material, thereby improving the mechanical properties of the product.

[0084] Test Example 2

[0085] The sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 were immersed in deionized water for 30 days. The mechanical properties of the materials before and after immersion were tested according to the standard GB / T1040.1-2018. The tensile strength retention rate and elongation at break retention rate were calculated. The results are shown in Table 2.

[0086] Table 2

[0087]

[0088] As shown in Table 2, the products obtained in Examples 1-3 of this invention maintained high tensile strength and elongation at break after water immersion, both exceeding those of Comparative Examples 1-4. Specifically, compared to Example 1, Comparative Example 3 replaced the modified carbon nanotubes with carbon nanotubes, and Comparative Example 4 omitted step a in the preparation of the modified carbon nanotubes and replaced the sulfonated carbon nanotubes in step b with carboxylated multi-walled carbon nanotubes. The retention rates of tensile strength and elongation at break for both were worse than those of Example 1. This is mainly attributed to the introduction of hexadecyltrimethoxysilane into the modified carbon nanotubes. The hydrophobic long-chain alkyl group of hexadecyltrimethoxysilane can form a low surface energy protective layer on the surface of the sulfonated carbon nanotubes, improving the material's water resistance.

[0089] Test Example 3

[0090] The oxygen index of the sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 of this invention was tested according to the test standard GB / T2406.2-2009, and the test results are recorded in Table 3.

[0091] Table 3

[0092]

[0093] As shown in Table 3, the products obtained in Examples 1-3 of this invention exhibit good flame retardant properties, with oxygen indices at relatively high levels. In Comparative Example 1, replacing the anti-aging agent with 3,5-di-tert-butyl-4-hydroxybenzaldehyde significantly reduced the oxygen index. In Comparative Example 2, replacing the anti-aging agent with a mixture of compound 1 and DOPO also slightly reduced the oxygen index. This is because the introduction of DOPO into the anti-aging agent causes its phosphorus-phenanthroline structure to decompose at high temperatures, releasing PO· free radicals, which exert a gas-phase flame retardant effect. Simultaneously, it promotes char formation, creating a dense phosphoric acid-nitrogen-containing carbon layer that insulates against heat and oxygen, thereby endowing the material with excellent flame retardant properties.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. An anti-aging cable comprising, from the inside to the outside, a conductor, an insulating layer and a sheath layer, characterized in that, The sheath layer comprises the following raw materials by weight: PVC resin 90-100 parts, linear low density polyethylene 15-20 parts, ethylene-octene copolymer 10-15 parts, plasticizer 12-18 parts, anti-aging agent 5-8 parts, calcium-zinc stabilizer 3-5 parts, modified carbon nanotube 3-5 parts, lubricant 2-3 parts; The anti-aging agent is prepared by the following preparation process: (1) 1,2,4,5-tetrazine-3,6-diamine is added into methanol, and then 3,5-di-tert-butyl-4-hydroxybenzaldehyde methanol solution is added for reaction; after the reaction is completed, it is concentrated under reduced pressure and separated to obtain compound 1; (2) Compound 1 is added into methanol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide methanol solution is added for reaction; after the reaction is completed, the reaction liquid is concentrated, filtered, washed and dried to obtain the anti-aging agent; The modified carbon nanotube is prepared by the following preparation process: a. Carboxylated multi-walled carbon nanotubes are added into anhydrous ethanol, and then dicyclohexyl carbodiimide is added to obtain a dispersion liquid; 4-aminobenzenesulfonic acid anhydrous ethanol solution is added into the dispersion liquid for stirring reaction; after filtration, washing and drying, sulfonated carbon nanotubes are obtained; b. The sulfonated carbon nanotubes are added into anhydrous ethanol A to obtain a dispersion liquid of sulfonated carbon nanotubes; hexadecyl trimethoxysilane is added into anhydrous ethanol B, and then water is added for stirring and mixing, and then the dispersion liquid of sulfonated carbon nanotubes is added for stirring reaction; After centrifugation, washing and drying, the modified carbon nanotube is obtained.

2. The anti-aging cable of claim 1, wherein, In step (1), the molar ratio of 1,2,4,5-tetrazine-3,6-diamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde is 1: (2-2.2); the amount ratio of 1,2,4,5-tetrazine-3,6-diamine and methanol is 1 mmol: 2-3 mL; the concentration of 3,5-di-tert-butyl-4-hydroxybenzaldehyde methanol solution is 1.1-1.5 mol / L; the reaction temperature is 50-60℃, and the reaction time is 0.5-1 h.

3. The anti-aging cable of claim 1, wherein, In step (2), the molar ratio of compound 1 and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1: (2-2.2); the amount ratio of compound 1 and methanol is 1 mmol: 2-3 mL; the concentration of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide methanol solution is 1.1-2 mol / L; the reaction temperature is 70-80℃, and the reaction time is 6-7 h.

4. The anti-aging cable of claim 1, wherein, In step a, the amount ratio of carboxylated multi-walled carbon nanotubes, dicyclohexyl carbodiimide and anhydrous ethanol is 1 g: 1.5-2.0 g: 200-250 mL; the volume ratio of the dispersion liquid and 4-aminobenzenesulfonic acid anhydrous ethanol solution is 1: (1-1.3), and the amount ratio of 4-aminobenzenesulfonic acid and anhydrous ethanol in the 4-aminobenzenesulfonic acid anhydrous ethanol solution is 1-2 g: 200-250 mL; the stirring reaction temperature is 50-60℃, and the stirring reaction time is 12-15 h.

5. The anti-aging cable of claim 1, wherein, In step b, the sulfonated carbon nanotubes, anhydrous ethanol A are used in a ratio of 1 g:200-250 mL; the sulfonated carbon nanotubes, hexadecyl trimethyl silane, anhydrous ethanol B and water are used in a ratio of 1 g:0.5-0.7 g:50 mL:2 mL; the stirring reaction is carried out at a temperature of 50-60℃ for 4-6h.

6. The anti-aging cable of claim 1, wherein, The plasticizer is dioctyl phthalate; the lubricant is zinc stearate; the calcium-zinc stabilizer is CZ-106-2.

7. A process for the preparation of an anti-aging cable according to any one of claims 1-6, characterized in that, The method comprises the following steps: S1. mixing PVC resin, linear low density polyethylene, ethylene-octene copolymer and calcium-zinc stabilizer at 80-90℃ for 10-12 min, continuously heating to 110-130℃, adding a mixture of plasticizer, anti-aging agent, modified carbon nanotubes and lubricant, and mixing for 5-8 min to obtain a sheath material; S2. coating an insulating layer on the surface of a conductor to obtain a conductor coated with an insulating layer; S3. extruding the sheath material obtained in step S1 through a double screw extruder to coat the sheath material on the surface of the insulating layer to form a sheath layer, thereby obtaining the anti-aging cable.

8. The method of claim 7, wherein the antioxidant cable is prepared by the steps of: The extrusion temperature of the double screw extruder is 150-190℃.

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