Anti-aging cable and preparation method thereof

Abstract

The invention belongs to the technical field of cable materials, and particularly relates to an anti-aging cable and a preparation method thereof. The anti-aging cable sequentially comprises a conductor, an insulating layer and a sheath layer from inside to outside, and the sheath layer is prepared from, by weight, 90-100 parts of PVC resin, 15-20 parts of linear low-density polyethylene, 10-15 parts of ethylene-octylene 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 nano tube and 2-3 parts of lubricant. Through molecular structure design, the prepared anti-aging agent not only can significantly improve the anti-aging performance of a cable sheath material, but also can effectively enhance the flame retardant property of the material. In addition, the modified carbon nanotube prepared by the invention can significantly improve the mechanical properties and waterproofness of the cable sheath material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cable materials, and particularly relates to an anti-aging cable and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the power and communication industries, the performance requirements of cables as key basic materials are increasingly improved, especially the long-term stability in harsh environments such as outdoors, high temperatures, and high humidity. The cable sheath layer, as the first barrier to protect the internal structure, needs to have excellent anti-aging, weather resistance, mechanical properties, and flame retardance. However, traditional cable sheath materials (such as PVC and polyethylene) are easily affected by ultraviolet light, oxygen, moisture, and metal ions during long-term use, leading to thermal oxidative aging, photo-oxidative degradation, and metal-catalyzed oxidation of the materials, and thus problems such as mechanical property degradation, cracking, and brittleness occur, which seriously affect the service life and safety of the cable.

[0003] Currently, the main means to improve the anti-aging performance of cable sheaths is to add antioxidants, light stabilizers, and the like. Traditional antioxidants such as hindered phenols and phosphite esters can delay the thermal oxidative aging of materials to some extent, but their molecular structures are single, the efficiency of capturing free radicals is limited, and they cannot simultaneously consider ultraviolet shielding and flame retardance. Light stabilizers such as ultraviolet absorbers and hindered amines can absorb ultraviolet light, but the synergistic effect with antioxidants is usually weak. In addition, existing flame retardants can improve the flame retardance of materials, but have a negative impact on the mechanical properties and environmental friendliness of the materials. Therefore, it is urgent to develop a new type of anti-aging cable sheath material that can improve the anti-aging properties, mechanical properties, and environmental adaptability of the material through molecular structure design and nanomodification technology, to meet the long-term stable use requirements of cables in complex working conditions. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, the primary purpose of the present application is to provide an anti-aging cable. The anti-aging agent prepared by the present application can not only significantly improve the anti-aging performance of the cable sheath material, but also effectively enhance the flame retardance of the material. Moreover, the modified carbon nanotubes prepared by the present application can significantly improve the mechanical properties and water resistance of the cable sheath material.

[0005] Another purpose of the present application is to provide a preparation method of an anti-aging cable. The method is simple to operate and easy to realize large-scale production.

[0006] The purpose of the present application is achieved by the following technical solutions: An anti-aging cable comprises a conductor, an insulation layer and a sheath layer from inside to outside, 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.

[0007] Further, 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.

[0008] Further, 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.

[0009] Further, 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, 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.

[0010] Further, in step a, the amount ratio of the carboxylated multi-walled carbon nanotube, the dicyclohexyl carbodiimide and the anhydrous ethanol is 1 g:1.5-2.0 g:200-250 mL; the volume ratio of the dispersion liquid and the anhydrous ethanol solution of 4-aminobenzenesulfonic acid is 1:(1-1.3), and the amount ratio of 4-aminobenzenesulfonic acid and anhydrous ethanol in the anhydrous ethanol solution of 4-aminobenzenesulfonic acid is 1-2 g:200-250 mL; the stirring reaction temperature is 50-60℃, and the time is 12-15 h.

[0011] Further, in step b, the amount ratio of the sulfonated carbon nanotube and the anhydrous ethanol A is 1 g:200-250 mL; the amount ratio of the sulfonated carbon nanotube, the hexadecyl trimethoxysilane, the anhydrous ethanol B and the 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.

[0012] Further, the plasticizer is dioctyl phthalate; the lubricant is zinc stearate; and the calcium-zinc stabilizer is CZ-106-2.

[0013] The application further provides a preparation method of the anti-aging cable, comprising 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 nanotube 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.

[0014] Further, the extrusion temperature of the double screw extruder is 150-190℃.

[0015] Compared with the prior art, the application has the following effects: 1. The anti-aging agent prepared by molecular structure design can not only significantly improve the anti-aging performance of the cable sheath material, but also effectively enhance the flame retardant performance of the material. The synergistic effect of the double hindered phenol structure and the 1,2,4,5-tetrazine ring structure in the anti-aging agent molecule can efficiently capture free radicals such as ·OH and ·OOH, delaying the thermal oxidation aging of the material; the tetrazine ring structure and the hindered amine in the molecule have a wide ultraviolet absorption capacity, which can effectively shield ultraviolet rays and reduce photo-oxidative degradation, and the nitrogen atom of the tetrazine ring can also chelate with copper ions in the cable to inhibit metal-catalyzed oxidation, further prolonging the service life of the material; and the phosphorus heterophane structure of DOPO decomposes at high temperature to release PO· free radicals, plays a gas phase flame retardant role, and at the same time promotes charring to form a dense phosphoric acid-nitrogen-containing carbon layer to insulate heat and oxygen, giving the material excellent flame retardant performance.

[0016] In addition, the amino group in the molecular structure of the anti-aging agent can improve the compatibility with the PVC matrix through hydrogen bonding, promote the uniform dispersion of the anti-aging agent, enable DOPO to stably embed in the material network, avoid the problem of mechanical property degradation caused by the migration of pure DOPO, and the conjugated system formed by the tetrazine ring and the phosphorus heterophane structure of DOPO can improve the molecular rigidity, reduce the chain segment movement, and further enhance the mechanical strength of the material.

[0017] 2. The sulfonated carbon nanotube is prepared by using the amidation reaction of carboxylated multi-walled carbon nanotubes and 4-aminobenzenesulfonic acid, and then the surface of the sulfonated carbon nanotube is modified by using hexadecyltrimethoxysilane (HDTMS), so that the modified carbon nanotube can significantly improve the mechanical properties and waterproofness of the cable sheath material. After the siloxane group of HDTMS is hydrolyzed, a stable Si-O-S covalent bond is formed with the sulfonic acid group on the surface of the sulfonated carbon nanotube, and the steric hindrance of the long-chain alkyl group can effectively improve the dispersion stability of the carbon nanotube; at the same time, the molecular chain entanglement effect between the long-chain alkyl group and the PVC resin matrix and the hydrogen bond interaction between the sulfonic acid group and the resin can not only further improve the interfacial compatibility of the carbon nanotube, but also effectively improve the stress transfer efficiency, thereby improving the strength and toughness of the material; in addition, the hydrophobic long-chain alkyl group of HDTMS can form a low-surface-energy protective layer on the surface of the sulfonated carbon nanotube, thereby improving the waterproofness of the material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The infrared spectrum of the modified carbon nanotube obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0019] The technical solutions of the present application are further described below in combination with specific embodiments. However, those skilled in the art should understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the present application. The specific conditions not mentioned in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if not specifically mentioned, are conventional products obtained through commercial channels.

[0020] The PVC resin of the present application 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 nanotube: inner diameter: 5-12 nm, outer diameter: 30-50 nm, length: 10-20 µm, -COOH > 2 wt%.

[0021] Example 1 An anti-aging cable, comprising a conductor, an insulation layer and a sheath layer from inside to outside, the sheath layer comprises the following raw materials by weight: PVC resin 95 parts, linear low density polyethylene 18 parts, ethylene-octene copolymer 12 parts, plasticizer (dioctyl phthalate) 15 parts, anti-aging agent 7 parts, calcium-zinc stabilizer (CZ-106-2) 4 parts, modified carbon nanotube 4 parts, lubricant (zinc stearate) 2.5 parts; The anti-aging agent is prepared by the following preparation process: (1) According to the amount ratio of 1,2,4,5-tetrazine-3,6-diamine and methanol of 1 mmol:2.5 mL, 1,2,4,5-tetrazine-3,6-diamine is added to methanol; under the condition of 55°C and stirring, slowly drop 3,5-di-tert-butyl-4-hydroxybenzaldehyde methanol solution with a concentration of 1.3 mol / L, the molar ratio of 1,2,4,5-tetrazine-3,6-diamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde is 1:2.1; after the drop is completed, continue to react for 0.75 h; after the reaction is completed, remove methanol and water under reduced pressure, separate with silica gel column (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] + Calculated 545.35, found 545.35.

[0022] (2) according to the amount ratio of compound 1 and methanol is 1 mmol:2.5 mL, compound 1 is added into methanol; under the condition of stirring at 75℃, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) methanol solution with a concentration of 1.5 mol / L is slowly added, the molar ratio of compound 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.1; after the dropwise addition is completed, the reaction is continued for 6.5 h; after the reaction is completed, the reaction liquid is concentrated to 1 / 3 of the original volume, ice water is added to precipitate the solid, which is 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] + Calculated 977.42, found 977.42.

[0023] The modified carbon nanotube is prepared by the following preparation process: a. carboxylated multi-walled carbon nanotubes are added into anhydrous ethanol, and dicyclohexyl carbodiimide is added, the amount ratio of carboxylated multi-walled carbon nanotubes, dicyclohexyl carbodiimide, anhydrous ethanol is 1 g:1.8 g:230 mL; ultrasonic treatment is performed for 35 min to obtain a dispersion liquid; the dispersion liquid is mixed with a 4-aminobenzenesulfonic acid anhydrous ethanol solution (the amount ratio of 4-aminobenzenesulfonic acid and anhydrous ethanol is 1.5 g:230 mL), the volume ratio of the dispersion liquid and the 4-aminobenzenesulfonic acid anhydrous ethanol solution is 1:1.2, and stirring is performed at 55℃ for 13 h; the collected crude product is sequentially washed with anhydrous ethanol and deionized water until the pH of the washing filtrate approaches 7, and finally vacuum dried to obtain sulfonated carbon nanotubes; b.The sulfonated carbon nanotubes were added into anhydrous ethanol A, and ultrasonic treatment was performed for 35 min to obtain a dispersion of the sulfonated carbon nanotubes; hexadecyl trimethoxysilane was added into anhydrous ethanol B, deionized water was added dropwise, and the mixture was stirred at room temperature for 35 min, and then the dispersion of the sulfonated carbon nanotubes was slowly added; the amount ratio of the sulfonated carbon nanotubes, hexadecyl trimethoxysilane, 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; the collected solid was washed with ethanol / water (v / v=1 / 1) for 2 times, and finally vacuum dried to obtain the modified carbon nanotubes.

[0024] The infrared spectrum of the modified carbon nanotubes is shown in FIG. 2. Figure 1 Compared with the carboxylated multi-walled carbon nanotubes, in the curve of the sulfonated carbon nanotubes, a strong peak of stretching vibration of amide C=O appeared at 1630 cm-1, characteristic peaks of amide N-H vibration appeared at 1574 cm-1 and 3326 cm-1, characteristic peaks of sulfonic acid group appeared at 1240 cm-1 and 1307 cm-1, which indicated that the synthesis of the sulfonated carbon nanotubes was successful. -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 The above results indicated that the long-chain hydrophobic alkyl of hexadecyl trimethoxysilane was successfully grafted.

[0025] The present embodiment also provides a preparation method of the anti-aging cable, which comprises the following steps: S1.PVC resin, linear low density polyethylene, ethylene-octene copolymer and calcium-zinc stabilizer were mixed at 85 °C for 11 min, and then the temperature was continuously increased to 120 °C; a mixture of plasticizer, anti-aging agent and modified carbon nanotubes and lubricant was added, and the mixture was mixed for 7 min to obtain a sheath material; S2.The insulating layer was coated on the surface of the conductor to obtain a conductor coated with an insulating layer; S3.The sheath material obtained in step S1 was extruded through a double screw extruder at an extrusion temperature of 180 °C; the sheath material was coated on the surface of the insulating layer to form a sheath layer, thereby obtaining an anti-aging cable.

[0026] Example 2 ​​​​​​​​​​An anti-aging cable comprises a conductor, an insulation layer and a sheath layer from inside to outside, the sheath layer comprises the following raw materials by weight: PVC resin 90 parts, linear low density polyethylene 15 parts, ethylene-octene copolymer 10 parts, plasticizer (dioctyl phthalate) 12 parts, anti-aging agent 5 parts, calcium-zinc stabilizer (CZ-106-2) 3 parts, modified carbon nanotube 3 parts, lubricant (zinc stearate) 2 parts; The anti-aging agent is prepared by the following preparation process: (1) According to the use amount ratio of 1,2,4,5-tetrazine-3,6-diamine and methanol is 1 mmol:2 mL, 1,2,4,5-tetrazine-3,6-diamine is added into methanol; under the condition of 50℃ and stirring, 3,5-di-tert-butyl-4-hydroxybenzaldehyde methanol solution with a concentration of 1.1 mol / L is slowly added dropwise, the molar ratio of 1,2,4,5-tetrazine-3,6-diamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde is 1:2; after the dropwise addition is completed, the reaction is continued for 0.5 h; after the reaction is completed, methanol and water are removed by concentration under reduced pressure, and the compound 1 is separated by silica gel column (petroleum ether / ethyl acetate=20 / 80); the 1H NMR and HRMS (ESI+) results of the compound 1 are the same as those of Example 1.

[0027] (2) According to the use amount ratio of compound 1 and methanol is 1 mmol:2 mL, compound 1 is added into methanol; under the condition of 70℃ and stirring, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide methanol solution with a concentration of 1.1 mol / L is slowly added dropwise, the molar ratio of compound 1 and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2; after the dropwise addition is completed, the reaction is continued for 6 h; after the reaction is completed, the reaction solution is concentrated to 1 / 3 of the original volume, and ice water is added to precipitate the solid, which is filtered, washed with water, and dried to obtain the anti-aging agent; the 1H NMR and HRMS (ESI+) results of the anti-aging agent are the same as those of Example 1.

[0028] The modified carbon nanotube is prepared by the following preparation process: a. Carboxylated multi-walled carbon nanotubes are added into anhydrous ethanol, and dicyclohexyl carbodiimide is added, the use amount ratio of carboxylated multi-walled carbon nanotubes, dicyclohexyl carbodiimide and anhydrous ethanol is 1 g:1.5 g:200 mL; ultrasonic treatment is carried out for 30 min to obtain a dispersion liquid; the dispersion liquid is mixed with 4-aminobenzenesulfonic acid anhydrous ethanol solution (the use amount ratio of 4-aminobenzenesulfonic acid and anhydrous ethanol is 1 g:200 mL), the volume ratio of the dispersion liquid and 4-aminobenzenesulfonic acid anhydrous ethanol solution is 1:1, and stirring is carried out at 50℃ for 15 h; the collected crude product is washed with anhydrous ethanol and deionized water in sequence until the pH of the washing filtrate approaches 7, and finally vacuum drying is carried out to obtain sulfonated carbon nanotubes; b. The sulfonated carbon nanotubes were added to anhydrous ethanol A in a ratio of 1 g:200 mL, and ultrasonic treatment was performed for 30 min to obtain a dispersion of the sulfonated carbon nanotubes; hexadecyl trimethoxysilane was added to anhydrous ethanol B, and after stirring at room temperature for 30 min, the dispersion of the sulfonated carbon nanotubes was slowly added in a ratio of 1 g:0.5 g:50 mL:2 mL; stirring was performed at 50°C for 6 h; centrifugation was performed, and the collected solid was washed twice with ethanol / water (v / v=1 / 1), and finally vacuum dried to obtain the modified carbon nanotubes.

[0029] The present embodiment also provides a preparation method of the anti-aging cable, comprising the following steps: S1. The PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer were mixed at 80°C for 12 min, and the temperature was continuously increased to 110°C; a mixture of plasticizer, anti-aging agent, modified carbon nanotubes, and lubricant was added, and mixing was performed for 8 min to obtain a sheath material; S2. The insulating layer was coated on the surface of the conductor to obtain a conductor coated with an insulating layer; S3. The sheath material obtained in step S1 was extruded through a double-screw extruder at an extrusion temperature of 150°C; the sheath material was coated on the surface of the insulating layer to form a sheath layer, thereby obtaining an anti-aging cable.

[0030] Example 3 An anti-aging cable comprises, from inside to outside, a conductor, an insulating layer, and a sheath layer; the sheath layer comprises the following raw materials in parts by weight: PVC resin 100 parts, linear low-density polyethylene 20 parts, ethylene-octene copolymer 15 parts, plasticizer (dioctyl phthalate) 18 parts, anti-aging agent 8 parts, calcium-zinc stabilizer (CZ-106-2) 5 parts, modified carbon nanotubes 5 parts, and lubricant (zinc stearate) 3 parts. The anti-aging agent is prepared by the following process: (1) 1,2,4,5-tetrazine-3,6-diamine was added to methanol in a ratio of 1 mmol:3 mL; a 3,5-di-tert-butyl-4-hydroxybenzaldehyde methanol solution with a concentration of 1.5 mol / L was slowly added dropwise under stirring at 60°C; the molar ratio of 1,2,4,5-tetrazine-3,6-diamine to 3,5-di-tert-butyl-4-hydroxybenzaldehyde was 1:2.2; after the dropwise addition was completed, the reaction was continued for 1 h; after the reaction was completed, methanol and water were removed by reduced pressure concentration, and silica gel column (petroleum ether / ethyl acetate=20 / 80) separation was performed to obtain compound 1; the 1H NMR and HRMS (ESI+) results of compound 1 were the same as those of Example 1.

[0031] (2) according to the amount ratio of compound 1 and methanol is 1 mmol: 3 mL, compound 1 is added into methanol; under the condition of stirring at 80℃, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide methanol solution with concentration of 2 mol / L is slowly added, the molar ratio of compound 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:2.2; after dropwise addition is completed, the reaction is continued for 7 h; after the reaction is completed, the reaction solution is concentrated to 1 / 3 of the original volume, ice water is added to precipitate the solid, which is filtered, washed with water, and dried to obtain the anti-aging agent; the 1H NMR and HRMS (ESI+) results of the anti-aging agent are the same as those of Example 1.

[0032] The modified carbon nanotube is prepared by the following preparation process: a. Carboxylated multi-walled carbon nanotubes are added to anhydrous ethanol, and dicyclohexyl carbodiimide is then added, with the amount ratio of carboxylated multi-walled carbon nanotubes, dicyclohexyl carbodiimide, and anhydrous ethanol being 1 g:2.0 g:250 mL; ultrasonic treatment is performed for 40 min to obtain a dispersion liquid; the dispersion liquid is mixed with a 4-aminobenzenesulfonic acid anhydrous ethanol solution (with the amount ratio of 4-aminobenzenesulfonic acid and anhydrous ethanol being 2 g:250 mL), with the volume ratio of the dispersion liquid and the 4-aminobenzenesulfonic acid anhydrous ethanol solution being 1:1.3, and stirring is performed at 60℃ for 12 h; filtration is performed, and the collected crude product is sequentially washed with anhydrous ethanol and deionized water until the pH of the washing filtrate approaches 7, and finally vacuum drying is performed to obtain sulfonated carbon nanotubes; b. According to the amount ratio of sulfonated carbon nanotubes and anhydrous ethanol A being 1 g:250 mL, the sulfonated carbon nanotubes are added to anhydrous ethanol A, and ultrasonic treatment is performed for 40 min to obtain a dispersion liquid of sulfonated carbon nanotubes; hexadecyl trimethoxysilane is added to anhydrous ethanol B, and after dropwise addition of deionized water and stirring at room temperature for 40 min, the dispersion liquid of sulfonated carbon nanotubes is slowly added, with the amount ratio of sulfonated carbon nanotubes, hexadecyl trimethoxysilane, anhydrous ethanol B, and water being 1 g:0.7 g:50 mL:2 mL; stirring is performed at 60℃ for 4 h; centrifugation is performed, and the collected solid is washed with ethanol / water (v / v=1 / 1) for 3 times, and finally vacuum drying is performed to obtain modified carbon nanotubes.

[0033] The embodiment also provides a preparation method of the anti-aging cable, including the following steps: S1. PVC resin, linear low-density polyethylene, ethylene-octene copolymer, and calcium-zinc stabilizer are mixed at 90℃ for 10 min, and then the temperature is continuously increased to 130℃, and a mixture of plasticizer, anti-aging agent, modified carbon nanotube, and lubricant is added, and mixing is performed for 5 min to obtain a sheath material; S2. coating the insulating layer on the surface of the conductor to obtain the conductor coated with the insulating layer; S3. extruding the sheath material obtained in step S1 through a double screw extruder, the extrusion temperature being 190℃; coating the sheath material on the surface of the insulating layer to form a sheath layer, thereby obtaining the anti-aging cable.

[0034] Comparative Example 1 The present comparative example 1 is basically the same as example 1, except that the anti-aging agent is replaced by 3,5-di-tert-butyl-4-hydroxybenzaldehyde.

[0035] Comparative Example 2 The present comparative example 2 is basically the same as example 1, except that the compound 1 prepared in step (1) of example 1 and DOPO are directly physically mixed.

[0036] Comparative Example 3 The present comparative example 3 is basically the same as example 1, except that the modified carbon nanotube is replaced by carboxylated multi-walled carbon nanotube.

[0037] Comparative Example 4 The present comparative example 4 is basically the same as example 1, except that in the preparation of the modified carbon nanotube, step a is omitted, and the sulfonated carbon nanotube in step b is replaced by carboxylated multi-walled carbon nanotube.

[0038] Test Example 1 (1) The tensile strength and elongation at break of the sheath layer obtained in examples 1-3 and comparative examples 1-4 are tested according to the standard of GB / T 1040.1-2018.

[0039] (2) In order to verify the anti-aging property of the sample, the sheath layer obtained in examples 1-3 and comparative examples 1-4 is placed in an aging oven according to the standard of GB / T 2951.12-2008, the light intensity of the sunlight lamp is set to 75W / m 2 , the ultraviolet radiation intensity is 60W / m 2 , the temperature in the oven is set to 60±2℃, and after 720h, the material is taken out again for testing the tensile strength and elongation at break; the tensile strength retention rate and the elongation at break retention rate are calculated, the retention rate = initial test index / aging test index x 100%; the specific test data are shown in table 1.

[0040] Table 1 From Table 1, it can be seen that 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 the modified carbon nanotube and other matrix components introduced in the application have good compatibility, which endows the material with good mechanical properties and anti-aging ability. In Comparative Example 1, the anti-aging agent is replaced by 3,5-di-tert-butyl-4-hydroxybenzaldehyde; in Comparative Example 2, the compound 1 prepared in step (1) of Example 1 and DOPO are directly physically mixed. Both Comparative Examples 1 and 2 have poorer mechanical properties than Examples 1-3, because the amino group introduced in 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 mechanical property degradation caused by the migration of DOPO. Moreover, the tetrazine ring in the anti-aging agent and the phosphorus-containing hetero ring structure of DOPO can improve the molecular rigidity, reduce the chain segment movement, and further enhance the mechanical strength of the material.

[0041] In Comparative Example 3, the modified carbon nanotube is replaced by carbon nanotube; in Comparative Example 4, during the preparation of the modified carbon nanotube, step a is omitted, and the sulfonated carbon nanotube in step b is replaced by carboxylated multi-walled carbon nanotube. The mechanical properties of Comparative Examples 3 and 4 are poorer than those of Example 1. The above phenomenon may be due to the following reasons: after the hydrolysis of the siloxane group of the modified carbon nanotube, a stable Si-O-S covalent bond is formed with the sulfonic acid group on the surface of the sulfonated carbon nanotube, which can effectively improve the dispersion stability of the carbon nanotube; at the same time, the molecular chain entanglement effect between the long-chain alkyl group and the PVC resin matrix and the hydrogen bond interaction between the sulfonic acid group and the resin can not only further improve the interfacial compatibility of the carbon nanotube, but also enhance the strength and toughness of the material, thereby improving the mechanical properties of the product.

[0042] Test Example 2 The sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 were immersed in deionized water for 30 days, and the mechanical properties of the material before and after immersion were tested according to the standard of GB / T1040.1-2018, and the tensile strength retention rate and elongation at break retention rate were calculated, and the results are shown in Table 2.

[0043] Table 2 As can be seen from Table 2, the tensile strength and elongation at break of the products obtained in Examples 1-3 of the present application are maintained at a high level after water immersion, and are higher than those of Comparative Examples 1-4. Among them, compared with Example 1, the tensile strength retention rate and elongation at break retention rate of Comparative Example 3 are worse because the modified carbon nanotubes are replaced by carbon nanotubes, and the tensile strength retention rate and elongation at break retention rate of Comparative Example 4 are worse because the sulfonated carbon nanotubes in step b are replaced by carboxylated multi-walled carbon nanotubes when preparing the modified carbon nanotubes. This is mainly due to the introduction of hexadecyl trimethoxysilane into the modified carbon nanotubes. The hydrophobic long-chain alkyl group of hexadecyl trimethoxysilane can form a low-surface-energy protective layer on the surface of the sulfonated carbon nanotubes, thereby improving the water resistance of the material.

[0044] Test Example 3 The oxygen index of the sheath layers obtained in Examples 1-3 and Comparative Examples 1-4 of the present application was tested according to the test standard of standard GB / T 2406.2-2009, and the test results are recorded in Table 3.

[0045] Table 3 As can be seen from Table 3, the products obtained in Examples 1-3 of the present application have good flame retardant performance, and the oxygen index is at a high level. Among them, the oxygen index of Comparative Example 1 is obviously decreased after the anti-aging agent is replaced by 3,5-di-tert-butyl-4-hydroxybenzaldehyde. The oxygen index of Comparative Example 2 is also slightly decreased after the anti-aging agent is replaced by a mixture of compound 1 and DOPO. This is because DOPO is introduced into the aging agent. The phosphorus hetero-fused structure of DOPO decomposes at high temperature, can release PO· free radicals, plays a gas-phase flame-retardant role, and at the same time promotes charring to form a dense phosphoric acid-nitrogen-containing carbon layer to insulate heat and oxygen, thereby endowing the material with excellent flame retardant performance.

[0046] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application, but not to limit it. The basic principles and main features of the present application have been described above with specific embodiments, and some modifications or replacements can be made on the basis of the present application, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the present application.

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.

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, The modified carbon nanotube is prepared by the following preparation process: a. Carboxylated multi-walled carbon nanotubes are added into anhydrous ethanol to obtain a dispersion liquid, then dicyclohexyl carbodiimide is added, and then 4-aminobenzenesulfonic acid anhydrous ethanol solution is added 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, then water is added for stirring, 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.

5. The anti-aging cable of claim 4, 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.

6. The anti-aging cable of claim 4, 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.

7. 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.

8. A process for the preparation of an anti-aging cable according to any one of claims 1 to 7, 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.

9. The method of claim 8, 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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