A corrosion-resistant carbon-based composite material and a method for producing the same

Abstract

This invention relates to a corrosion-resistant carbon-based composite material and its preparation method, belonging to the technical field of carbon-based composite materials. The invention involves creating a self-made modifier, then using this modifier and oxalic acid to dope aniline to obtain doped polyaniline. The doped polyaniline is then blended with high-density polyethylene and carbon nanotubes to obtain the corrosion-resistant carbon-based composite material. The phosphate ester groups in the modifier not only provide flame retardancy but also form complexes with the metal wire core. Together with the hydrophobic protective layer formed by the long-chain alkyl groups, they block the intrusion of water molecules and chemical media, giving the material excellent corrosion resistance. Furthermore, the aromatic heterocyclic structure in the modifier improves the overall heat resistance of the material and, in combination with the long-chain alkyl groups, ensures uniform dispersion of polyaniline and carbon nanotubes in the polyethylene matrix, enhancing the interfacial bonding between the three components, thereby improving the overall electrical conductivity and corrosion resistance of the material.

Description

Technical Field

[0001] This invention belongs to the field of carbon-based composite material technology. Specifically, it relates to a corrosion-resistant carbon-based composite material and its preparation method, and more specifically, it relates to a carbon-based composite conductive plastic for use in cable sheath materials and its preparation method. Background Technology

[0002] Conductive plastics, as functional materials that combine the easy processing, low cost, and corrosion resistance of polymers with the conductivity of metals, have broad application prospects in fields such as antistatic agents, electromagnetic shielding, corrosion protection, and organic electronic devices. The mainstream technical approach to achieving conductivity in plastics is to fill an insulating polymer matrix with conductive substances, such as carbon black, metal powder, or carbon fiber.

[0003] To form an effective conductive pathway, a large amount of conductive filler is usually required. This severely degrades the mechanical properties of the matrix resin, leading to brittleness, reduced toughness, and poor processing flowability, while also significantly increasing costs. Furthermore, most conductive fillers have a large surface energy difference with the polyolefin matrix, resulting in weak interfacial bonding. This not only hinders the uniform dispersion of the filler but also creates defects at the interface, becoming stress concentration points and further accelerating the decline in the material's mechanical properties. To address these issues, existing technologies often blend intrinsically conductive polymers with general-purpose plastics such as polyethylene. Polyaniline monomers offer good environmental stability and adjustable conductivity. By blending polyaniline with general-purpose plastics like polyethylene, the filler content can be reduced to produce high-performance conductive composite materials. However, the polyaniline backbone is highly rigid, and strong π-π interactions exist between molecular chains, making phase separation highly likely and forming macroscopic polyaniline aggregates that cannot form an effective conductive network.

[0004] Based on this, the present invention will provide a method for preparing a corrosion-resistant carbon-based composite material. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant carbon-based composite material and its preparation method, in order to solve the problems mentioned in the background art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a corrosion-resistant carbon-based composite material includes the following steps:

[0008] Step 1: Add hydroxy aromatic heterocycle, long-chain alkyl ethylene oxide, sodium hydroxide and toluene to a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at 60-80℃ for 2-4 hours. After the reaction is completed, cool to room temperature, wash the product with saturated brine and evaporate to dryness to obtain the modifier precursor.

[0009] The second step involves adding the modifier precursor, phosphorus trichloride, acid-binding agent, and toluene into a three-necked flask, attaching a condenser and a thermometer, turning on the magnetic stirrer, and reacting at 5–15°C for 2–4 hours. After the reaction is complete, the mixture is cooled to room temperature and then evaporated to dryness to obtain the modifier.

[0010] The third step involves adding aniline, modifier, ammonium persulfate and oxalic acid solution to a three-necked flask, attaching a condenser and thermometer, turning on magnetic stirring, and reacting at 0–5°C for 16–24 hours. After the reaction is complete, the mixture is filtered, and the resulting solid is washed with ethanol and dried to obtain doped polyaniline.

[0011] The fourth step involves mixing high-density polyethylene, doped polyaniline, carbon nanotubes, and antioxidants evenly, then adding the mixture to a screw extruder for melt extrusion and granulation to obtain a corrosion-resistant carbon-based composite material.

[0012] Furthermore, the hydroxy aromatic heterocycle in the first step is one of 1-hydroxynaphthalene, 1-hydroxyphenanthrene, and 1-hydroxypyrene.

[0013] Furthermore, the long-chain alkyl ethylene oxide in the first step is one of 2-undecylethylene oxide, 2-tetanedecylethylene oxide, and 2-pentadedecylethylene oxide.

[0014] Furthermore, in the first step, the mass ratio of hydroxyl aromatic heterocycle, long-chain alkyl ethylene oxide, sodium hydroxide, and toluene is 7.3–14: 13.5–17.5: 0.06–0.08: 80–120.

[0015] Furthermore, the acid-binding agent in the second step is at least one of pyridine, 4-dimethylaminopyridine, and triethanolamine.

[0016] Furthermore, in the second step, the mass ratio of the modifier precursor, phosphorus trichloride, acid binder and toluene is 16.5–21.5: 3–3.8: 4.2–5.4: 80–100.

[0017] Furthermore, the oxalic acid solution in the third step has a mass fraction of 5-10%.

[0018] Furthermore, in the third step, the mass ratio of aniline, modifier, ammonium persulfate and oxalic acid solution is 10-20:14-18:25-50:48-96.

[0019] Furthermore, the antioxidant in the fourth step is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 164.

[0020] Furthermore, in the fourth step, the mass ratio of high-density polyethylene, doped polyaniline, carbon nanotubes, and antioxidant is 70–80:15–20:10–15:0.3–0.6.

[0021] Furthermore, the temperature of melt extrusion in the fourth step is 160–180°C.

[0022] A corrosion-resistant carbon-based composite material is prepared by any of the above preparation steps.

[0023] The beneficial effects of this invention are:

[0024] The phosphite groups in the modifier of this invention decompose upon heating during combustion, inhibiting the combustion chain reaction and preventing the spread of flames; and promote the carbonization of the surface of combustibles to form a dense protective carbon layer, ensuring that the conductive path remains stable and reliable after a fault and will not be interrupted by a fire.

[0025] The phosphite groups in the modifier of this invention can form complexes with the surface of the galvanized steel or copper-clad steel of the grounding electrode, ensuring close contact between the conductive material and the metal electrode. This effectively prevents poor contact caused by thermal expansion and contraction or moisture, and also acts as a passivation agent, effectively preventing corrosion of the galvanized steel or copper-clad steel grounding material. Furthermore, the strongly hydrophobic long-chain alkyl groups, when enriched on the material surface, form a hydrophobic protective layer that effectively blocks the intrusion of water molecules and the erosion of various chemical media, significantly improving the durability of the material, ensuring the long-term stability of the grounding resistance, and thus extending the life of the entire cable.

[0026] The aromatic heterocyclic structure in the modifier of this invention improves the overall heat resistance of the material while being firmly adsorbed onto the surfaces of carbon nanotubes and polyaniline through π-π interactions without disrupting their hybrid structure. This effectively prevents the aggregation of carbon nanotube fillers and polyaniline, allowing them to be more uniformly dispersed in the polyethylene matrix. This achieves effective interfacial electronic coupling, facilitating electron transitions between the conductive filler, polyaniline, and matrix, thereby enhancing the conductivity and interfacial bonding properties of the carbon-based composite material. Furthermore, the long-chain alkyl groups in the modifier have good compatibility with polyethylene and can be adsorbed onto the polyethylene chains and carbon nanotube surfaces through entanglement. The synergy between the aromatic heterocyclic structure and the long-chain alkyl groups enhances the adhesion between polyaniline, polyethylene, and carbon nanotubes. This ensures the long-term physical integrity of the carbon-based conductive composite plastic, thereby improving the overall conductivity and corrosion resistance of the material. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a corrosion-resistant carbon-based composite material includes the following steps:

[0030] Step 1: Add 7.3g of 1-hydroxynaphthalene, 13.5g of 2-undecyl ethylene oxide, 0.06g of sodium hydroxide and 80g of toluene to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 60℃ for 4h. After the reaction is complete, cool to room temperature, wash the product with saturated brine and evaporate to dryness to obtain the modifier precursor.

[0031] The second step involves adding 16.5g of the modifier precursor, 3g of phosphorus trichloride, 4.2g of pyridine and 80g of toluene into a three-necked flask, attaching a condenser and a thermometer, turning on the magnetic stirrer, and reacting at 5°C for 4 hours. After the reaction is complete, the mixture is cooled to room temperature and then evaporated to dryness to obtain the modifier.

[0032] The third step involves adding 10g of aniline, 14g of modifier, 25g of ammonium persulfate and 48g of 10% oxalic acid solution to a three-necked flask, attaching a condenser and thermometer, turning on magnetic stirring, and reacting at 0℃ for 24 hours. After the reaction is complete, the mixture is filtered, and the resulting solid is washed with ethanol and dried to obtain doped polyaniline.

[0033] Step 4: Mix 70g of high-density polyethylene, 15g of doped polyaniline, 15g of carbon nanotubes and 0.3g of antioxidant 1010 evenly and add them to a screw extruder. Melt extrusion is performed at 160℃ to obtain a corrosion-resistant carbon-based composite material.

[0034] A corrosion-resistant carbon-based composite material is prepared by the above preparation steps.

[0035] Example 2

[0036] A method for preparing a corrosion-resistant carbon-based composite material includes the following steps:

[0037] Step 1: Add 11.6g of 1-hydroxyphenanthrene, 15.5g of 2-tridecyl ethylene oxide, 0.07g of sodium hydroxide and 100g of toluene to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 70℃ for 3h. After the reaction is complete, cool to room temperature, wash the product with saturated brine and evaporate to dryness to obtain the modifier precursor.

[0038] Step 2: Add 19g of modifier precursor, 3.4g of phosphorus trichloride, 4.8g of 4-dimethylaminopyridine and 90g of toluene to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 10℃ for 3h. After the reaction is completed, cool to room temperature and then evaporate to dryness to obtain the modifier.

[0039] The third step involves adding 15g of aniline, 16g of modifier, 37.5g of ammonium persulfate and 64g of 7.5% oxalic acid solution to a three-necked flask, attaching a condenser and thermometer, turning on magnetic stirring, and reacting at 2.5℃ for 20 hours. After the reaction is complete, the mixture is filtered, and the resulting solid is washed with ethanol and dried to obtain doped polyaniline.

[0040] Step 4: Mix 75g of high-density polyethylene, 17.5g of doped polyaniline, 12.5g of carbon nanotubes and 0.45g of antioxidant 1076 evenly and add them to a screw extruder. Melt extrusion is performed at 170℃ to obtain a corrosion-resistant carbon-based composite material.

[0041] A corrosion-resistant carbon-based composite material is prepared by the above preparation steps.

[0042] Example 3

[0043] A method for preparing a corrosion-resistant carbon-based composite material includes the following steps:

[0044] Step 1: Add 14g of 1-hydroxypyrene, 17.5g of 2-pentadecanyl ethylene oxide, 0.08g of sodium hydroxide and 120g of toluene to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 80℃ for 2h. After the reaction is complete, cool to room temperature, wash the product with saturated brine and evaporate to dryness to obtain the modifier precursor.

[0045] The second step involves adding 21.5g of the modifier precursor, 3.8g of phosphorus trichloride, 5.4g of triethanolamine and 100g of toluene into a three-necked flask, attaching a condenser and a thermometer, turning on the magnetic stirrer, and reacting at 5°C for 2 hours. After the reaction is complete, the mixture is cooled to room temperature and then evaporated to dryness to obtain the modifier.

[0046] The third step involves adding 20g of aniline, 18g of modifier, 50g of ammonium persulfate and 96g of 5% oxalic acid solution to a three-necked flask, attaching a condenser and thermometer, turning on magnetic stirring, and reacting at 5°C for 16 hours. After the reaction is complete, the mixture is filtered, and the resulting solid is washed with ethanol and dried to obtain doped polyaniline.

[0047] Step 4: Mix 80g of high-density polyethylene, 20g of doped polyaniline, 10g of carbon nanotubes and 0.6g of antioxidant 164 evenly and add them to a screw extruder. Melt extrusion is performed at 180°C to obtain a corrosion-resistant carbon-based composite material.

[0048] A corrosion-resistant carbon-based composite material is prepared by the above preparation steps.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 2 is that no modifier is added during the preparation of doped polyaniline, while the other raw materials and preparation steps remain unchanged.

[0051] Experimental Example 1

[0052] The corrosion-resistant carbon-based composite materials in Examples 1-3 and Comparative Examples 1 and 2 were subjected to performance tests. The tensile strength and elongation at break of each group of corrosion-resistant carbon-based composite materials were tested according to GB / T2951.21-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables". The tensile strength retention rate and elongation at break retention rate after immersion in 3% sulfuric acid aqueous solution at 85°C for 24 hours were also tested according to GB / T31489-2015 "Extruded Insulated Power Cable System for DC Transmission with Rated Voltage of 500kV and Below". The flame retardancy rating of each group of corrosion-resistant carbon-based composite materials was tested according to GB / T41879-2022 "Fire Resistance Test of Fiber Reinforced Polymer Composites with Plastic Combustion Performance". The test results are shown in Table 1.

[0053] Table 1

[0054]

[0055] As can be seen from Table 1, compared with Comparative Example 1, Examples 1-3 have higher tensile strength, elongation at break, tensile strength retention rate, elongation at break retention rate, and flame retardancy rating, and lower volume resistivity. This indicates that Examples 1-3 have better mechanical strength, corrosion resistance, electrical conductivity, and flame retardancy than Comparative Example 1. Combined with Comparative Example 1, this demonstrates that the modifier can effectively improve the mechanical strength, corrosion resistance, electrical conductivity, and flame retardancy of corrosion-resistant carbon-based composite materials.

[0056] The foregoing has provided a detailed description of a corrosion-resistant carbon-based composite material and its preparation method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in the present invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technologies falling within the scope of the claims.

Claims

1. A method for preparing a corrosion-resistant carbon-based composite material, characterized in that, Includes the following steps: Preparation of modifier: The modifier precursor is obtained by nucleophilic substitution reaction of hydroxy aromatic heterocycle and long-chain alkyl ethylene oxide, and then the modifier is obtained by nucleophilic substitution reaction of the modifier precursor with phosphorus trichloride under the action of an acid binder. Preparation of corrosion-resistant carbon-based composite materials: Aniline is doped with a modifier, ammonium persulfate and oxalic acid solution to obtain doped polyaniline, and then the doped polyaniline is melt-blended with high-density polyethylene, carbon nanotubes and antioxidant to obtain corrosion-resistant carbon-based composite materials. The long-chain alkyl ethylene oxide is one of 2-undecyl ethylene oxide, 2-tetanedecyl ethylene oxide, and 2-pentadedecyl ethylene oxide; The hydroxy aromatic heterocycle is one of 1-hydroxynaphthalene, 1-hydroxyphenanthrene, and 1-hydroxypyrene; The mass ratio of hydroxyl aromatic heterocycles to long-chain alkyl ethylene oxide is 7.3–14:13.5–17.5, and the mass ratio of modifier precursor, phosphorus trichloride, and acid-binding agent is 16.5–21.5:3–3.8:4.2–5.

4. The mass ratio of aniline, modifier, ammonium persulfate, and oxalic acid solution is 10–20:14–18:25–50:48–96, and the mass ratio of high-density polyethylene, doped polyaniline, carbon nanotubes, and antioxidant is 70–80:15–20:10–15:0.3–0.

6.

2. The method for preparing a corrosion-resistant carbon-based composite material according to claim 1, characterized in that, The acid-binding agent is at least one of pyridine, 4-dimethylaminopyridine, and triethanolamine.

3. The method for preparing a corrosion-resistant carbon-based composite material according to claim 1, characterized in that, The oxalic acid solution has a mass fraction of 5-10%.

4. The method for preparing a corrosion-resistant carbon-based composite material according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 164.

5. The method for preparing a corrosion-resistant carbon-based composite material according to claim 1, characterized in that, The temperature for melt extrusion is 160–180℃.

6. A corrosion-resistant carbon-based composite material, characterized in that, A corrosion-resistant carbon-based composite material is prepared by the preparation method described in any one of claims 1 to 5.

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