An antistatic agent, its preparation method and application

Abstract

The present invention relates to an antistatic agent, a preparation method thereof and an application, belonging to the technical field of plastic additives, and solves at least one of the problems of poor dispersibility, insufficient conductivity, easy oxidation, insufficient thermal stability and uniformity, and easy aggregation or sedimentation of the existing antistatic agent. The preparation method of the antistatic agent of the present invention includes steps such as silane coupling agent modification, polyaniline coating, and silica loading to obtain a novel SiO2-CNTs composite material. The antistatic agent has good dispersibility, excellent conductivity, good thermal stability and uniformity. Treating ultra-high molecular weight polyethylene fibers with an oil agent prepared by using the above antistatic agent helps to improve the continuity and uniformity of the fibers during the production process, and reduce the incidence of breakage and defects; and the fibers have excellent high temperature resistance and antistatic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic additives, and particularly to an antistatic agent, a preparation method thereof, and an application thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fibers have been widely used in many fields due to their excellent mechanical properties, such as bulletproof vests, cut-resistant gloves, ropes, fishing nets, and medical devices. UHMWPE fibers have extremely high strength, excellent wear resistance, low friction coefficient, and good impact resistance. However, this kind of fiber also has some significant disadvantages in practical applications, mainly including poor heat resistance and poor antistatic performance.

[0003] The melting point of UHMWPE fibers is relatively low, about 130°C, which is much lower than that of other high-performance fibers (such as aramid fibers). In a high-temperature environment, UHMWPE fibers are prone to deformation and degradation, resulting in a significant decline in their mechanical properties. For example, in industrial high-temperature environment applications, the heat resistance of materials directly affects their service life and safety. In addition, heat treatment processes involved in textile processing, such as heat setting and ironing, will also have an adverse impact on UHMWPE fibers, restricting their application in these fields.

[0004] The antistatic performance of UHMWPE fibers is poor, mainly because its own conductivity is extremely low, and it is easy to accumulate static electricity during use. The accumulation of static electricity will not only affect the processing performance of the fibers, for example, it is easy to adsorb dust and impurities during spinning, weaving, and post-finishing processes, resulting in a decline in product quality; at the same time, in certain specific environments, such as flammable and explosive environments, the accumulation of static electricity may cause fires or explosions, bringing serious safety hazards.

[0005] Currently, in view of the problems of poor heat resistance and poor antistatic performance of UHMWPE fibers, there are already some modification methods and treatment technologies on the market. For example, by coating high-temperature resistant materials on the fiber surface to improve its heat resistance, or adding antistatic agents to improve its antistatic performance. However, existing antistatic agents have problems such as poor dispersibility, insufficient conductivity, easy oxidation, insufficient thermal stability and uniformity, and easy aggregation or sedimentation, resulting in poor thermal stability, easy breakage, and high static voltage of the treated ultra-high molecular weight polyethylene (UHMWPE) fibers.

[0006] Therefore, it is necessary to develop an antistatic agent with good dispersibility, conductivity, and thermal stability, as well as a special oil agent for ultra-high molecular weight polyethylene (UHMWPE) fibers. Summary of the Invention

[0007] In view of the above analysis, the embodiments of the present invention aim to provide an antistatic agent and a preparation method and application thereof, so as to solve at least one of the problems of existing antistatic agents, such as poor dispersibility, insufficient conductivity, easy oxidation, insufficient thermal stability and uniformity, and easy aggregation or sedimentation.

[0008] The invention provides a method for preparing an antistatic agent, which comprises: firstly modifying carbon nanotubes with a silane coupling agent, then coating the modified carbon nanotubes with polyaniline, and finally loading the modified carbon nanotubes coated with polyaniline on a silicon dioxide carrier to obtain a finished SiO2-CNTs composite material, namely the antistatic agent.

[0009] The specific steps are as follows:

[0010] S1: weighing or measuring carbon nanotubes and ethanol, adding the carbon nanotubes into the ethanol and performing ultrasonic dispersion to obtain a carbon nanotube solution;

[0011] S2: taking a quantity of silane coupling agent and dissolving it in ethanol, slowly adding distilled water under stirring conditions, adjusting the pH value, and allowing the mixed solution to stand until the silane coupling agent is fully hydrolyzed to obtain a silane coupling agent solution;

[0012] S3: slowly adding the carbon nanotube solution into the silane coupling agent solution and stirring, and obtaining a reaction mixture after the reaction is completed;

[0013] S4: baking the reaction mixture, cooling it to room temperature and then vacuum drying it to obtain carbon nanotubes modified with a silane coupling agent;

[0014] S5: ultrasonically dispersing the carbon nanotubes modified with the silane coupling agent in an aqueous solution and adding aniline, stirring and mixing the mixture thoroughly; cooling the mixture in an ice bath and adding an ammonium persulfate solution, stirring the mixture at 0°C, and after the reaction is completed, filtering, washing and drying the mixture to obtain the polyaniline-coated carbon nanotubes;

[0015] S6: adding the polyaniline-coated carbon nanotubes to an aqueous solution containing sodium dodecylbenzene sulfonate, and subjecting the solution to ultrasonic treatment to obtain a carbon nanotube suspension; slowly adding silicon dioxide powder to the carbon nanotube suspension, stirring evenly, and heating and continuing to stir to obtain a composite semi-finished product;

[0016] S7: drying and heat treating the semi-finished composite material, and after cooling, screening and washing to obtain a finished SiO2-CNTs composite material, namely the antistatic agent.

[0017] Specifically, in step S1, the mass ratio of carbon nanotubes to ethanol is 1:100-120.

[0018] Specifically, in step S2, the volume ratio of the silane coupling agent to ethanol is 1:10 - 12; the volume ratio of the silane coupling agent to distilled water is 1:3 - 3.5; the pH value adjustment range is 4 - 5, and the standing time is ≥ 2 h; the silane coupling agent is KH-550 or KH-560.

[0019] Specifically, in step S3, the mass ratio of the silane coupling agent solution to the carbon nanotube solution is 0.2 - 0.4:1, and the stirring time is ≥ 4 hours.

[0020] Specifically, the specific operation of step S4 is: transferring the reaction mixture to a constant temperature oven and keeping it warm at 80 - 100 °C for 12 - 14 hours; after cooling to room temperature, drying the reaction mixture in a vacuum drying oven for 24 - 30 hours to obtain carbon nanotubes modified with a silane coupling agent.

[0021] Specifically, in step S5, the mass ratio of the carbon nanotubes modified with a silane coupling agent to aniline is 1:6 - 10; the mass ratio of ammonium persulfate to aniline is 0.05 - 0.1:1, and the reaction time is 4 - 6 hours.

[0022] Specifically, in step S6, the mass concentration of the sodium dodecylbenzenesulfonate aqueous solution is 1 - 1.2%, the volume ratio of the carbon nanotubes coated with polyaniline to the sodium dodecylbenzenesulfonate aqueous solution is 1:400 - 500; the mass ratio of the silica powder to the carbon nanotubes coated with polyaniline is 8 - 15:1, the heating temperature is 80 °C - 100 °C, and the reaction time is ≥ 3 hours.

[0023] Specifically, the specific operation of step S7 for heat treatment is to dry the semi-finished composite material in air, and then heat it to 500 ± 100 °C at a heating rate of 5 ± 1 °C / min in a tube furnace, and the treatment time is 120 - 160 min.

[0024] The present invention also discloses an antistatic agent, which is prepared by the above preparation method.

[0025] The present invention also discloses an oil agent for ultra-high molecular weight polyethylene fibers, and the oil agent includes the above antistatic agent.

[0026] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0027] 1. The antistatic agent provided by the present invention has good antistatic performance, and excellent dispersion, conductivity, antioxidant property, and thermal stability; the static voltage of the ultra-high molecular weight polyethylene fibers treated with the oil agent containing the antistatic agent is ≤ 0.041 kV, the initial modulus is ≥ 1900 cN / dtex, the initial breaking strength is ≥ 40.0 cN / dtex, and the decrease in the breaking strength under high temperature conditions is small.

[0028] The present invention uses carbon nanotubes as the main matrix of the antistatic agent. Carbon nanotubes have good thermal and electrical conductivity, so they can be used as good thermal and antistatic materials. However, due to their unique carbon structure, the surface of carbon nanotubes is mainly hydrophobic, which makes their dispersibility in sizing agents (organic solvents) poor. The present invention modifies them with silane coupling agents. The siloxane groups can form covalent bonds with the functional groups (such as carboxyl groups, hydroxyl groups, etc.) on the surface of carbon nanotubes through condensation reactions, thereby anchoring on the surface of carbon nanotubes. By introducing flexible chain segments to provide sufficient steric hindrance, direct contact between carbon nanotubes and the action of van der Waals forces are avoided. The modified carbon nanotubes are not easily aggregated or re-aggregated, making it easier for them to interact with organic molecules in the sizing agent, thus improving the dispersibility of carbon nanotubes in the sizing agent.

[0029] Polyaniline has good electrical conductivity compared to other polymers and is rich in π-electron systems like carbon nanotubes. The continuous electron transport network formed through π-π stacking interactions can effectively improve the overall electrical conductivity of the material. Carbon nanotubes provide fast electron transport channels, and the conductivity of polyaniline further enhances these channels. This enhanced electron transport ability enables charges to be quickly conducted on the surface or within the material, thereby effectively dissipating electrostatic accumulation and reducing the generation and accumulation of static electricity. Further, through π-π interactions, the polyaniline molecular chains form a uniform and continuous coating layer on the surface of carbon nanotubes, which can serve as a physical barrier to prevent the oxidation of carbon nanotubes during processing or application.

[0030] Silica has excellent thermal stability and can maintain its physical and chemical properties unchanged in high-temperature environments, thus providing a stable substrate for the entire composite material. By introducing carbon nanotubes coated with polyaniline supported by silica carriers in the spinning sizing agent, the thermal stability of the fibers during processing and application can be increased, especially in environments that need to withstand high-temperature treatment or operation, to avoid losses or decomposition of the antistatic agent under high-temperature conditions and thus failure. On the other hand, the surface roughness and pore structure of silica microparticles also contribute to the physical embedding or attachment of carbon nanotubes, reducing the sedimentation or aggregation of carbon nanotubes in the sizing agent. Ensuring that the processing quality and performance of each batch of fibers are consistent. This improved dispersibility contributes to the continuity and uniformity of the fibers during production, reducing the incidence of breakage and defects.

[0031] The static voltage of ultra-high molecular weight polyethylene fibers treated with the sizing agent containing the antistatic agent is ≤0.041 kV, the initial modulus is ≥1900 cN / dtex, the initial breaking strength is ≥40.0 cN / dtex, and the decrease in breaking strength under high-temperature conditions is small.

[0032] 2. When preparing the antistatic agent using the preferred process parameters of the present invention, the uniformity and stability of the antistatic agent product can be improved, including but not limited to the sufficient modification of the silane coupling agent, the uniformity and appropriate thickness of the polyaniline coating, and the loading effect of the silica carrier, etc.

[0033] 3. For the antistatic agent and oil agent provided by the present invention, the raw materials and equipment are readily available and can be directly purchased; the preparation process is relatively simple, the process conditions are relatively mild, the preparation difficulty is low, and the existing oiling process can be used for oiling, which is suitable for large-scale production and wide application.

[0034] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the content specifically pointed out in the specification and the drawings. Brief Description of the Drawings

[0035] The drawings are only for the purpose of showing specific embodiments and are not considered to limit the present invention. Throughout the drawings, the same reference signs represent the same components.

[0036] Figure 1 It is a physical photo of the oil agent for ultra-high molecular weight polyethylene fibers in Example 1;

[0037] Figure 2 It is a flow chart for the preparation of the antistatic agent. Detailed Embodiments

[0038] Next, the preferred embodiments of the present invention will be specifically described in conjunction with the drawings. The drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0039] The present invention provides a method for preparing an antistatic agent. The method includes: first, modifying carbon nanotubes with a silane coupling agent, then coating the modified carbon nanotubes with polyaniline, and finally loading the polyaniline-coated modified carbon nanotubes on a silica carrier to obtain a finished SiO2-CNTs composite material, that is, the antistatic agent.

[0040] The present invention uses carbon nanotubes as the main matrix of the antistatic agent. Carbon nanotubes have good thermal and electrical conductivity, so they can be used as good thermal and antistatic materials. However, due to their unique carbon structure, the surface of carbon nanotubes is mainly hydrophobic, which makes their dispersibility in sizing agents (organic solvents) poor. The present invention modifies them with silane coupling agents. The siloxane groups can form covalent bonds with the functional groups (such as carboxyl groups, hydroxyl groups, etc.) on the surface of carbon nanotubes through condensation reactions, thereby anchoring on the surface of carbon nanotubes. By introducing flexible chain segments to provide sufficient steric hindrance, direct contact between carbon nanotubes and the action of van der Waals forces are avoided. The modified carbon nanotubes are not easily aggregated or re-aggregated, making it easier for them to interact with organic molecules in the sizing agent, thus improving the dispersibility of carbon nanotubes in the sizing agent.

[0041] Polyaniline has good conductivity compared to other polymers and is rich in π-electron systems like carbon nanotubes. The continuous electron transport network formed through π-π stacking interactions can effectively improve the overall conductivity of the material. Carbon nanotubes provide fast electron transport channels, and the conductivity of polyaniline further enhances these channels. This enhanced electron transport ability enables charges to be quickly conducted on the surface or within the material, thereby effectively dissipating electrostatic accumulation and reducing the generation and accumulation of static electricity. Further, through π-π interactions, the polyaniline molecular chains form a uniform and continuous coating layer on the surface of carbon nanotubes, which can serve as a physical barrier to prevent the oxidation of carbon nanotubes during processing or application.

[0042] Silica has excellent thermal stability and can maintain its physical and chemical properties unchanged in high-temperature environments, thus providing a stable substrate for the entire composite material. By introducing carbon nanotubes coated with polyaniline supported on silica carriers into the spinning sizing agent, the thermal stability of the fibers during processing and application can be increased, especially in environments that require exposure to high-temperature processing or operations, to avoid losses or decomposition of the antistatic agent under high-temperature conditions and thus failure. On the other hand, the surface roughness and pore structure of silica microparticles also contribute to the physical embedding or attachment of carbon nanotubes, reducing the sedimentation or aggregation of carbon nanotubes in the sizing agent. Ensuring that the processing quality and performance of each batch of fibers are consistent. This improved dispersibility contributes to the continuity and uniformity of the fibers during production, reducing the incidence of breaks and defects.

[0043] Specifically, it includes the following steps:

[0044] S1: Weigh or measure carbon nanotubes and ethanol, add the carbon nanotubes to ethanol and perform ultrasonic dispersion to obtain a carbon nanotube solution;

[0045] S2: Measure the silane coupling agent and dissolve it in ethanol. Slowly add distilled water under stirring conditions and adjust the pH value. Let the mixed solution stand still until the silane coupling agent is fully hydrolyzed to obtain a silane coupling agent solution;

[0046] S3: Slowly add the carbon nanotube solution to the silane coupling agent solution and stir. After the reaction is completed, obtain a reaction mixture;

[0047] S4: Bake the reaction mixture, cool it to room temperature and then perform vacuum drying to obtain carbon nanotubes modified with a silane coupling agent;

[0048] S5: Ultrasonically disperse the carbon nanotubes modified with a silane coupling agent in an aqueous solution and add aniline. Stir to make them fully mixed; Cool in an ice bath and add an ammonium persulfate solution. Continue to stir at 0 °C. After the reaction is completed, filter, wash and dry to obtain carbon nanotubes coated with polyaniline;

[0049] S6: Add the carbon nanotubes coated with polyaniline to an aqueous solution containing sodium dodecylbenzenesulfonate. After ultrasonic treatment, obtain a carbon nanotube suspension; Slowly add silicon dioxide powder to the carbon nanotube suspension. After stirring evenly, heat and continue to stir to obtain a semi-finished composite material;

[0050] S7: Dry and heat-treat the semi-finished composite material. After cooling, sieve and wash to obtain the finished SiO2-CNTs composite material, which is the antistatic agent.

[0051] Specifically, the main purpose of step S1 is to pretreat the carbon nanotubes. Add the carbon nanotubes to ethanol and use an ultrasonic processor to ultrasonically disperse them for more than 30 minutes, which can effectively remove impurities and aggregates on the surface of the carbon nanotubes.

[0052] Specifically, the mass ratio of carbon nanotubes to ethanol in step S1 is 1:100 - 120. If the amount of carbon nanotubes added is too much, the impurity removal effect is not good; if the amount of carbon nanotubes added is too little, the preparation / production efficiency will be reduced.

[0053] Specifically, in step S2, the volume ratio of the silane coupling agent to ethanol is 1:10 - 12; the volume ratio of the silane coupling agent to distilled water is 1:3 - 3.5; the pH value adjustment range is 4 - 5, and the standing time is ≥ 2 h; the silane coupling agent is KH-550 or KH-560. The hydrolysis reaction of silane coupling agents (such as KH-550 or KH-560) in water is significantly affected by the pH value. Under neutral or slightly acidic conditions, the hydrolysis rate of these coupling agents is moderate, which is beneficial to controlling the reaction progress and product quality. If the pH value is too high (alkaline), the silane coupling agent may hydrolyze too quickly, resulting in unstable products; if the pH value is too low (too acidic), the hydrolysis of the coupling agent may be inhibited, affecting the final reaction effect. A pH value in the range of 4 to 5 helps the silicon alkyl groups on the silane coupling agent to react more effectively with the functional groups (such as carboxyl groups, hydroxyl groups, etc.) on the surface of the carbon nanotubes. This coupling effect can improve the interfacial compatibility, making the modified carbon nanotubes better dispersed in the final composite material. At the specified pH value and standing time (at least 2 hours), preferably 2 - 6 hours, it can ensure that the silane coupling agent is fully hydrolyzed without excessive polymerization, which is beneficial to subsequent processing and applications. Sufficient hydrolysis is the premise to ensure that the coupling agent can effectively act on the carbon nanotubes and other matrix materials.

[0054] Specifically, the pH value regulator used is potassium hydroxide or triethanolamine.

[0055] Specifically, in step S3, the mass ratio of the silane coupling agent solution to the carbon nanotube solution is 0.2 - 0.4:1, and the stirring time is ≥ 4 hours to ensure sufficient contact and reaction between the carbon nanotubes and the coupling agent. The siloxane groups can form covalent bonds with the functional groups (such as carboxyl groups, hydroxyl groups) on the surface of the carbon nanotubes through a condensation reaction, thereby anchoring on the surface of the carbon nanotubes. By introducing flexible chain segments to provide sufficient steric hindrance, the direct contact between the carbon nanotubes and the action of van der Waals forces are avoided. The modified carbon nanotubes are not easily aggregated or re-aggregated, making it easier for them to interact with the organic molecules in the sizing agent, thus improving the dispersibility of the carbon nanotubes in the sizing agent.

[0056] Specifically, the specific operation of step S4 is: transfer the reaction mixture to a constant temperature oven and keep it warm at 80 - 100 °C for 12 - 14 hours; after cooling to room temperature, dry the reaction mixture in a vacuum drying oven for 24 - 30 hours to obtain carbon nanotubes modified with a silane coupling agent.

[0057] Specifically, in step S5, the mass ratio of the carbon nanotubes modified with silane coupling agent to aniline is 1:6 to 100. Use a magnetic stirrer to stir at room temperature to ensure sufficient mixing of aniline and the carbon nanotubes modified with silane coupling agent. Here, water is only used as a solvent or dispersion matrix and will be removed through subsequent drying and other processes. Therefore, the amount of water added only needs to ensure its dispersion effect, and the specific dosage can be adjusted according to the actual situation, not too much or too little. Cool the mixed solution in an ice bath, slowly add the pre-dissolved ammonium persulfate solution, and initiate the polymerization reaction. The mass ratio of ammonium persulfate (here referring to the solute mass) to aniline is 0.05 to 0.1:1, the reaction time is 4 to 6 hours, and the reaction temperature is 0 °C (ice bath).

[0058] The mass ratio of the carbon nanotubes modified with silane coupling agent to aniline (1:6 to 100) is in this range to ensure the full use of aniline, enabling it to undergo a uniform polymerization reaction on the surface of the carbon nanotubes. The carbon nanotubes serve as the core, and aniline polymerizes on its surface to form a polyaniline coating layer. If too much aniline is added, it may lead to the residue of unreacted aniline, which will affect the electrical properties and thermal stability of the composite material. If too little is added, it may not be sufficient to completely cover the carbon nanotubes, resulting in a decrease in conductivity and mechanical properties.

[0059] The mass ratio of ammonium persulfate to aniline (0.05 to 0.1:1). As an initiator, the dosage of ammonium persulfate should appropriately control the polymerization reaction rate and degree of polymerization of aniline. This ratio is to ensure the controllability of the reaction and the uniformity of the product. Too much ammonium persulfate may cause the polymerization reaction to be too fast, affecting the growth of polyaniline chains and making the distribution of polyaniline uneven. Too little may lead to incomplete polymerization reaction and reduce the performance of the product.

[0060] Reaction temperature control (0 °C). Conducting the reaction in an ice bath can greatly control the polymerization rate and slow down the reaction, thus facilitating the obtaining of a more uniform polyaniline coating layer. The 0 °C environment helps reduce side reactions and unwanted polymerization reaction paths. In the 0 °C ice bath environment, the formation of polyaniline is through a radical polymerization reaction initiated by the initiator ammonium persulfate. Aniline molecules are first oxidized by ammonium persulfate to form radicals, and these radicals then link to form polyaniline chains. Low temperature helps control the reaction rate, reduce chain breakage and non-specific reactions, and thus obtain a more uniform polyaniline layer.

[0061] Specifically, separate the solid and liquid by filtration, wash the precipitate with a large amount of distilled water to remove unreacted monomers and by-products. Transfer the washed carbon nanotubes (in the process state) to a vacuum drying oven and dry at 60 to 80 °C for no less than 24 hours to obtain carbon nanotubes coated with polyaniline.

[0062] It should be noted that polyaniline has good conductivity compared to other polymers. Both polyaniline and carbon nanotubes are rich in π - electron systems. The continuous electron transport network formed through π - π stacking interactions can effectively improve the overall conductivity of the material. Carbon nanotubes provide fast electron transport channels, and the conductivity of polyaniline further enhances these channels. This enhanced electron transport ability enables charges to quickly conduct on the surface or within the material, thereby effectively dissipating the electrostatic accumulation and reducing the generation and accumulation of static electricity. Further, through π - π interactions, the polyaniline molecular chains form a uniform and continuous coating layer on the surface of carbon nanotubes, which can serve as a physical barrier to prevent the oxidation of carbon nanotubes during processing or application.

[0063] Specifically, in step S6, the mass concentration of the sodium dodecylbenzenesulfonate aqueous solution is 1 - 1.2%, the volume ratio of the polyaniline - coated carbon nanotubes to the sodium dodecylbenzenesulfonate aqueous solution is 1:400 - 500, and the ultrasonic treatment time is ≥1 h to obtain a well - dispersed carbon nanotube suspension; the mass ratio of the silica powder to the polyaniline - coated carbon nanotubes is 8 - 15:1, the heating temperature is 80°C - 100°C, and the reaction time is ≥3 hours to make the combination of silica and carbon nanotubes more compact.

[0064] It should be noted that silica has excellent thermal stability and can maintain its physical and chemical properties unchanged in high - temperature environments, thus providing a stable substrate for the entire composite material. By introducing polyaniline - coated carbon nanotubes supported by silica carriers into the spinning finish, the thermal stability of the fibers during processing and application can be increased, especially in environments that require exposure to high - temperature treatment or operation. On the other hand, the surface roughness and pore structure of the silica microparticles also contribute to the physical embedding or attachment of carbon nanotubes, reducing the sedimentation or aggregation of carbon nanotubes in the finish. Ensuring that the processing quality and performance of each batch of fibers are consistent. This improved dispersibility contributes to the continuity and uniformity of the fibers during production, reducing the incidence of breakage and defects.

[0065] Specifically, in step S7, the semi - finished composite material can be dried in air.

[0066] Specifically, the specific operation of the heat treatment in step S7 is to dry the composite material semi-finished product in the air, and then heat it in a tube furnace at a heating rate of 5±1 °C / min to 500±100 °C, and the treatment time is 120-160 min. Heat treatment can promote the physical and chemical combination between different components in the composite material. For example, between the carbon nanotubes coated with polyaniline and silica, heat treatment can promote better combination between silica, carbon nanotubes and polyaniline, enhancing the overall structural stability of the composite material. Secondly, through the heating process, residual solvents and moisture in the composite material can be removed, further improving the thermal stability of the material. This is particularly important for materials used in high-temperature environments, which can ensure that their performance in actual applications will not be reduced due to high temperatures. For composite materials containing conductive polymers (such as polyaniline) and carbon nanotubes, heat treatment can help form a more continuous and uniform conductive network, improving the overall conductivity of the material.

[0067] After cooling, unreacted materials are removed through conventional screening and washing processes to obtain the final SiO2-CNTs composite material.

[0068] The present invention also discloses an antistatic agent, which is prepared by the above preparation method.

[0069] The present invention also discloses an oil agent for ultra-high molecular weight polyethylene fibers, and the oil agent includes the antistatic agent described above.

[0070] Specifically, the oil agent is suitable for ultra-high molecular weight polyethylene fibers and includes a smoothing agent, an emulsifier, an antistatic agent and a stabilizer; by mass, 50-70 parts of the smoothing agent, 50-60 parts of the emulsifier, 4-8 parts of the antistatic agent, and 1-2 parts of the stabilizer.

[0071] The functions and content determination bases of each component are as follows:

[0072] Smoothing agent: The smoothing agent can reduce the friction coefficient of the fiber in processes such as spinning, drawing, texturing, spinning and weaving, and improve the oil film strength, thereby protecting the fiber. If the amount of the smoothing agent is too small, the lubricity of the fiber surface will be insufficient, and the fiber is likely to break during the processing; if the amount is too large, the fiber surface may be too smooth, affecting the bonding force between the fibers. Through experimental verification, when the smoothing agent is 50-70 parts, the comprehensive performance of the oil agent is better.

[0073] Emulsifier: By reducing the interfacial tension between the oil and water phases, two immiscible liquids can form a stable emulsion (that is, ensuring the uniformity of the oil agent). If the amount of the emulsifier is too small, the oil agent will be unevenly distributed on the fiber surface, affecting the lubrication effect; if the amount is too large, the cost may increase, and the mechanical properties of the fiber may be affected. Through experimental verification, when the emulsifier is 50-60 parts, the comprehensive performance of the oil agent is better.

[0074] Antistatic agent: If the amount of the antistatic agent used is too small, it cannot effectively reduce the static electricity accumulation; if the amount used is too large, it may affect the mechanical properties and feel of the fiber. Through experimental verification, when the amount of the antistatic agent is 4 - 8 parts, the comprehensive performance of the oil agent is better.

[0075] Stabilizer: The stabilizer can improve the stability, high-temperature resistance, sunlight resistance, storage resistance of the oil agent, as well as its dispersibility during high-speed processing. If the amount of the stabilizer used is too small, the oil agent will fail during high-temperature or long-term use; if the amount used is too large, it will affect the oiling effect and comprehensive performance of the oil agent. Through experimental verification, when the amount of the stabilizer is 1 - 2 parts, the comprehensive performance of the oil agent is better.

[0076] Synergistic effect: The combined use of the antistatic agent with the smoothing agent and the emulsifier can effectively reduce the static electricity problem without affecting the basic physical properties of the fiber, enabling the fiber to maintain good fluidity and processability during high-speed processing.

[0077] When the smoothing agent and the emulsifier are used in appropriate proportions, an oil agent with both good lubricity and excellent dispersibility can be formed, which helps to provide a continuous and uniform lubricating protective layer during spinning, weaving and other processes, reducing the risk of broken filaments and fiber damage.

[0078] Furthermore, the smoothing agent is one or more of lauryl oleate, isooctyl oleate, isooctyl stearate, triolein, mineral oil. The above substances have good lubricity, can increase the softness of the fiber, and have excellent lubricity and stability, can effectively reduce the friction between fibers, and have certain antioxidant properties.

[0079] Furthermore, the emulsifier is one or more of cardanol polyoxyethylene ether, polyglycerol monofatty acid ester, castor oil polyoxyethylene ether. The above substances have good emulsifying properties and chemical stability, are non-irritating to the fiber, and have certain lubricating effects.

[0080] Furthermore, the antistatic agent selected is the antistatic agent described in the present invention.

[0081] Furthermore, the stabilizer is one or more of polyether silicone oil acrylate, Tween 80, polyether-modified silicone oil, trifluoropropylmethyl silicone oil. These stabilizers all have high chemical stability, can maintain their structures unchanged under various processing and use conditions, thus ensuring the long-term effectiveness of the performance of the oil agent; these stabilizers can all improve the lubricity and dispersibility of the oil agent, ensuring the smoothness and uniform coating of the fiber during processing; these stabilizers can all show good stability under different temperature and environmental conditions, especially in high-temperature and high-speed industrial applications, which helps to protect the performance of the fiber during processing and use.

[0082] Specifically, the sizing agent has excellent antistatic performance. After being treated with the sizing agent, the static voltage of the ultra-high molecular weight polyethylene fiber is ≤ 0.041 kV, the initial modulus is ≥ 1900 cN / dtex, the initial breaking strength is ≥ 40.0 cN / dtex, and the breaking strength decreases less under high temperature conditions. After the fiber is placed in an oven at 200 °C for 72 h and then taken out, the decrease in breaking strength is ≤ 9.2%.

[0083] The present invention also discloses a preparation method of the above sizing agent, and the specific steps are as follows:

[0084] S21: Weigh raw materials according to a preset formula, put the smoothing agent and the emulsifier into a stirring tank, and stir evenly at room temperature;

[0085] S22: While continuing to stir, slowly add the antistatic agent to ensure that the antistatic agent is evenly dispersed in the whole mixture;

[0086] S23: Add a stabilizer to the mixture, continue to stir for more than 30 minutes to ensure that all components are fully fused, and obtain a semi-finished sizing agent;

[0087] S24: Adjust the pH value and viscosity of the semi-finished sizing agent, filter and fill it into a storage container to obtain the finished sizing agent.

[0088] Specifically, the stirring speed in step S21 is 800 - 1000 r / min. If the stirring speed is too slow, the mixing effect is not good, and if the speed is too fast, too many foams will be generated.

[0089] Specifically, the pH value regulator is potassium hydroxide or triethanolamine.

[0090] Specifically, the pH value range is 6 - 7, and the viscosity range is 100 mPa·s - 115 mPa·s.

[0091] Specifically, the viscosity of the mixture can be adjusted by adding an appropriate amount of distilled water or a suitable diluent (one or more of ethanol, acetone, and water).

[0092] The present invention also discloses a use method (sizing method) of the above sizing agent, which specifically includes the following steps:

[0093] S31: Prepare an ultra-high molecular weight polyethylene high-viscosity solution;

[0094] S32: Extrude the high-viscosity solution through a spinning nozzle, the nozzle diameter is 1 mm, the length-diameter ratio is 6 - 12, to form fine filaments, and the spinning temperature is 250 °C - 280 °C, to obtain ultra-high molecular weight polyethylene fibers;

[0095] S33: After the fibers are initially cooled, they are immediately sent to a stretching machine for thermal stretching; the stretching temperature is set at 120°C to 140°C, and the stretching ratio is 5 to 10 times the original length;

[0096] S34: The stretched fibers are oiled through a coating device, and after being cooled and dried, they are wound onto a reel to obtain the finished fiber product.

[0097] Exemplarily, an ultra-high molecular weight polyethylene high-viscosity solution can be obtained by the following method: Mix UHMWPE powder with a solvent (one or several of p-xylene / decalin, tetralin, kerosene, liquid paraffin, white oil) in a heated and stirred container, and heat it sufficiently to 130°C to 160°C to completely dissolve it to form a high-viscosity solution; the mass content of ultra-high molecular weight polyethylene is 15% to 18%.

[0098] Specifically, the coating device described in step S34 is a dipping tank or a spray system, and the oiling speed is 20 m / min to 30 m / min to ensure that the fibers are evenly coated with the oiling agent.

[0099] Specifically, the cooling described in step S34 can be air cooling or water bath cooling, and the cooling time is 10 to 20 s to stabilize the coating of the oiling agent on the fiber surface.

[0100] Further, generally, the specifications of the wound fiber product are 5 to 10 kg / roll.

[0101] Description of the sources of raw materials for testing:

[0102] Ultra-high molecular weight polyethylene was purchased from Zhejiang Jiuding Chemical Materials Co., Ltd., grade: U-PE350-II, molecular weight was 3,500,000 - 8,000,000 g / mol, and the bulk density was 0.30 - 0.50 g / cm 3 .

[0103] Multi-walled carbon nanotubes were purchased from Xianfeng Nano, model XFM22, purity was 95%, length was 0.5 μm - 2 μm, and diameter was 20 nm - 30 nm.

[0104] Silica was purchased from AGC Chemicals (Shanghai) Co., Ltd., average particle size was 5 - 10 μm, surface area was 800 m 2 / g, and the pore volume was 3 cm 3 / g.

[0105] Aniline was purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd.

[0106] Example 1

[0107] Preparation of the antistatic agent:

[0108] S1: weighing or measuring 1 part of carbon nanotubes and 100 parts of ethanol by weight, adding the carbon nanotubes into the ethanol and performing ultrasonic dispersion to obtain a carbon nanotube solution;

[0109] S2: According to the volume ratio, 1 part of KH-550 was measured and dissolved in 10 parts of ethanol, and 3 parts of distilled water were slowly added under stirring, and the pH value was adjusted to 4. The mixed solution was allowed to stand for 3 hours until the silane coupling agent was fully hydrolyzed to obtain a silane coupling agent solution;

[0110] S3: slowly adding the carbon nanotube solution into the silane coupling agent solution and stirring for 4 hours, and obtaining a reaction mixture after the reaction is completed; the mass ratio of the silane coupling agent to the carbon nanotube is 0.2:1.

[0111] S4: baking the reaction mixture, cooling it to room temperature and then vacuum drying it to obtain carbon nanotubes modified with a silane coupling agent.

[0112] S5: Ultrasonic dispersion of carbon nanotubes modified with silane coupling agent in aqueous solution and addition of aniline, stirring and mixing thoroughly; ice-cooling and addition of ammonium persulfate solution, stirring continued at 0°C for 5 hours, after the reaction was completed, filtering, washing and drying to obtain polyaniline-coated carbon nanotubes; the mass ratio of carbon nanotubes modified with silane coupling agent to aniline was 1:6, and aniline:ammonium persulfate = 1:0.05.

[0113] S6: Adding polyaniline-coated carbon nanotubes to an aqueous solution containing 1 wt.% sodium dodecylbenzene sulfonate at a mass ratio of 1:400, and obtaining a carbon nanotube suspension after ultrasonic treatment; slowly adding silica powder to the carbon nanotube suspension, stirring evenly, heating to 90°C and continuing stirring for 3 hours to obtain a composite material semi-finished product; the mass ratio of silica to polyaniline-coated carbon nanotubes is 8:1.

[0114] S7: Dry the semi-finished composite material in air, and then heat it to 500±100°C in a tubular furnace at a heating rate of 5±1°C / min for 120 to 160 min. After cooling, the semi-finished composite material is sieved and washed to obtain a finished SiO2-CNTs composite material, i.e., the antistatic agent.

[0115] Oil configuration:

[0116] The preset formula is: by mass, 50 parts of lauryl oleate as a lubricant, 50 parts of cardanol polyoxyethylene ether as an emulsifier, 5 parts of an antistatic agent, and 1 part of acrylic acid polyether silicone oil as a stabilizer.

[0117] S21: weigh the raw materials according to the preset formula, put the smoothing agent and emulsifier into a stirring tank, and stir them evenly at room temperature at a stirring speed of 900 r / min;

[0118] S22: While continuing to stir, slowly add the antistatic agent to ensure that the antistatic agent is evenly dispersed throughout the mixture;

[0119] S23: Add a stabilizer to the mixture and continue stirring for more than 30 minutes to ensure that all components are fully blended to obtain a semi-finished oil agent;

[0120] S24: Adjust the pH value of the semi-finished oil agent to 6 and the viscosity to 110 mPa·s, filter and fill it into a storage container, which is the finished oil agent.

[0121] Oiling process:

[0122] S31: Prepare a solution of ultra-high molecular weight polyethylene with high viscosity;

[0123] The ultra-high molecular weight polyethylene high-viscosity solution can be obtained by the following method: Mix UHMWPE powder with white oil in a heated and stirred container, heat it fully to 130 °C to completely dissolve it to form a high-viscosity solution; the content of ultra-high molecular weight polyethylene is 15 wt.%.

[0124] S32: Extrude the high-viscosity solution through a spinning nozzle with a nozzle diameter of 1 mm and a length-diameter ratio of 6 to form filaments at a spinning temperature of 250 °C to obtain ultra-high molecular weight polyethylene fibers;

[0125] S33: After the fibers are initially cooled, immediately send them to a stretching machine for thermal stretching; the stretching temperature is set at 120 °C and the stretching ratio is 5 times the original length;

[0126] S34: Oil the stretched fibers through a coating device at an oiling speed of 20 m / min. After oiling, cool and dry them, and then wind them on a reel to obtain finished fibers.

[0127] Example 2

[0128] Preparation of antistatic agent:

[0129] S1: Weigh or measure 1 part of carbon nanotubes and 120 parts of ethanol by weight components, add the carbon nanotubes to the ethanol and perform ultrasonic dispersion to obtain a carbon nanotube solution;

[0130] S2: Measure 1 part of KH-560 by volume ratio and dissolve it in 11 parts of ethanol. Slowly add 3.5 parts of distilled water under stirring conditions and adjust the pH value to 4.5. Let the mixed solution stand for 2.5 h until the silane coupling agent is fully hydrolyzed to obtain a silane coupling agent solution;

[0131] S3: Slowly add the carbon nanotube solution to the silane coupling agent solution and stir for 4.5 h. After the reaction is completed, a reaction mixture is obtained; the mass ratio of the silane coupling agent to the carbon nanotubes is 0.4:1.

[0132] S4: Bake the reaction mixture, cool it to room temperature and then conduct vacuum drying to obtain carbon nanotubes modified with silane coupling agent.

[0133] S5: Ultrasonically disperse the carbon nanotubes modified with silane coupling agent in an aqueous solution and add aniline, stir and mix them thoroughly; cool in an ice bath and add ammonium persulfate solution, continue to stir at 0 °C for 4 h. After the reaction is completed, filter, wash and dry to obtain carbon nanotubes coated with polyaniline; the mass ratio of the carbon nanotubes modified with silane coupling agent to aniline is 1:10, and aniline:ammonium persulfate = 1:0.1.

[0134] S6: Add the carbon nanotubes coated with polyaniline to an aqueous solution containing 1.1 wt.% sodium dodecylbenzenesulfonate, with a mass ratio of 1:500, and obtain a carbon nanotube suspension after ultrasonic treatment; slowly add silica powder to the carbon nanotube suspension, stir evenly, heat to 85 °C and continue to stir for 3.5 h to obtain a semi-finished composite material; the mass ratio of silica to the carbon nanotubes coated with polyaniline is 13:1.

[0135] S7: Dry the semi-finished composite material in air, then heat it to 500 ± 100 °C in a tube furnace at a heating rate of 5 ± 1 °C / min, with a treatment time of 120 - 160 min. After cooling, sieve and wash to obtain the finished SiO2-CNTs composite material, which is the antistatic agent.

[0136] Configuration of the oil agent:

[0137] The preset formula is: by mass parts, 70 parts of isooctyl oleate as a leveling agent, 53 parts of polyglycerol monostearate as an emulsifier, 6 parts of antistatic agent, and 1.5 parts of Tween 80 as a stabilizer.

[0138] The preparation method and oiling method of the oil agent are the same as those in Example 1.

[0139] Example 3

[0140] Preparation of the antistatic agent:

[0141] S1: By weight components, weigh or measure 1 part of carbon nanotubes and 110 parts of ethanol, add the carbon nanotubes to ethanol and conduct ultrasonic dispersion to obtain a carbon nanotube solution;

[0142] S2: By volume ratio, measure 1 part of KH-550 and dissolve it in 12 parts of ethanol, slowly add 3 parts of distilled water under stirring conditions, and adjust the pH value to 5. Let the mixed solution stand for 4 h until the silane coupling agent is fully hydrolyzed to obtain a silane coupling agent solution;

[0143] S3: slowly adding the carbon nanotube solution into the silane coupling agent solution and stirring for 5 hours, and obtaining a reaction mixture after the reaction is completed; the mass ratio of the silane coupling agent to the carbon nanotube is 0.3:1.

[0144] S4: baking the reaction mixture, cooling it to room temperature and then vacuum drying it to obtain carbon nanotubes modified with a silane coupling agent.

[0145] S5: Ultrasonic dispersion of carbon nanotubes modified with silane coupling agent in aqueous solution and addition of aniline, stirring and mixing thoroughly; ice-cooling and addition of ammonium persulfate solution, stirring continued at 0°C for 4.5h, after the reaction was completed, filtration, washing and drying were performed to obtain polyaniline-coated carbon nanotubes; the mass ratio of carbon nanotubes modified with silane coupling agent to aniline was 1:8, and aniline:ammonium persulfate = 1:0.07.

[0146] S6: Adding polyaniline-coated carbon nanotubes to an aqueous solution containing 1.2wt.% sodium dodecylbenzenesulfonate at a mass ratio of 1:480, and obtaining a carbon nanotube suspension after ultrasonic treatment; slowly adding silica powder to the carbon nanotube suspension, stirring evenly, heating to 95°C and continuing stirring for 3h to obtain a composite material semi-finished product; the mass ratio of silica to polyaniline-coated carbon nanotubes is 10:1.

[0147] S7: Dry the semi-finished composite material in air, and then heat it to 500±100°C in a tubular furnace at a heating rate of 5±1°C / min for 120 to 160 min. After cooling, the semi-finished composite material is sieved and washed to obtain a finished SiO2-CNTs composite material, i.e., the antistatic agent.

[0148] Oil configuration:

[0149] The preset formula is: by mass, 65 parts of lubricant isooctyl stearate, 60 parts of emulsifier castor oil polyoxyethylene ether, 8 parts of antistatic agent, and 1.8 parts of stabilizer polyether modified silicone oil.

[0150] The preparation method of the oil agent and the oiling method are the same as those in Example 1.

[0151] Example 4

[0152] Preparation of antistatic agent:

[0153] S1: weigh or measure 1 part of carbon nanotubes and 105 parts of ethanol by weight, add the carbon nanotubes into the ethanol and perform ultrasonic dispersion to obtain a carbon nanotube solution;

[0154] S2: According to the volume ratio, 1 part of KH-560 was measured and dissolved in 10 parts of ethanol, and 3.5 parts of distilled water were slowly added under stirring, and the pH value was adjusted to 4.5. The mixed solution was allowed to stand for 3 hours until the silane coupling agent was fully hydrolyzed to obtain a silane coupling agent solution;

[0155] S3: slowly adding the carbon nanotube solution into the silane coupling agent solution and stirring for 4 hours, and obtaining a reaction mixture after the reaction is completed; the mass ratio of the silane coupling agent to the carbon nanotube is 0.25:1.

[0156] S4: baking the reaction mixture, cooling it to room temperature and then vacuum drying it to obtain carbon nanotubes modified with a silane coupling agent.

[0157] S5: Ultrasonic dispersion of carbon nanotubes modified with silane coupling agent in aqueous solution and adding aniline, stirring and mixing thoroughly; cooling in an ice bath and adding ammonium persulfate solution, stirring is continued at 0°C for 6 hours, and after the reaction is completed, polyaniline-coated carbon nanotubes are obtained by filtering, washing and drying; the mass ratio of carbon nanotubes modified with silane coupling agent to aniline is 1:7, and aniline:ammonium persulfate = 1:0.09.

[0158] S6: Adding polyaniline-coated carbon nanotubes to an aqueous solution containing 1 wt.% sodium dodecylbenzene sulfonate at a mass ratio of 1:430, and obtaining a carbon nanotube suspension after ultrasonic treatment; slowly adding silica powder to the carbon nanotube suspension, stirring evenly, heating to 80°C and continuing stirring for 3.5 hours to obtain a composite material semi-finished product; the mass ratio of silica to polyaniline-coated carbon nanotubes is 15:1.

[0159] S7: Dry the semi-finished composite material in air, and then heat it to 500±100°C in a tubular furnace at a heating rate of 5±1°C / min for 120 to 160 min. After cooling, the semi-finished composite material is sieved and washed to obtain a finished SiO2-CNTs composite material, i.e., the antistatic agent.

[0160] Oil configuration:

[0161] The preset formula is: by mass, 55 parts of smoothing agent glyceryl trioleate, 23 parts of emulsifier cardanol polyoxyethylene ether + 34 parts of polyglycerol monofatty acid ester, 4 parts of antistatic agent, and 2 parts of stabilizer trifluoropropyl methyl silicone oil.

[0162] The preparation method of the oil agent and the oiling method are the same as those in Example 1.

[0163] Comparative Example 1

[0164] Compared with Example 4, the carbon nanotubes are not modified with a silane coupling agent (no steps S2 and S3), and the other process conditions and operations are the same.

[0165] Comparative Example 2

[0166] Compared with Example 4, polyethylene glycol was used to replace polyaniline to coat carbon nanotubes, and the remaining process conditions and operations were the same.

[0167] Comparative Example 3

[0168] Compared with Example 4, the process of loading carbon nanotubes on silica was omitted (step S6 was absent), and the remaining process conditions and operations were the same.

[0169] Performance detection:

[0170] Test standards for the breaking strength and initial modulus of ultra-high molecular weight polyethylene fibers: Refer to GB / T19975-2005 Test Method for Tensile Properties of High-Strength Chemical Fibre Filaments. The static voltage was measured using a Keyence SK-H electrostatic measuring instrument. High-temperature test: The fiber was placed in an oven at 200 °C and kept for 72 h and then taken out, and its breaking strength was tested. The test results are shown in Table 1.

[0171] Table 1 List of properties of ultra-high molecular weight polyethylene fibers

[0172]

[0173] It can be seen from the above table that in Comparative Example 1, since the carbon nanotubes were not modified with a silane coupling agent, the carbon nanotubes aggregated and piled up, resulting in a decrease in antistatic performance, an increase in static voltage, and a lack of the reinforcing effect of the carbon nanotubes, leading to a decrease in the initial modulus and breaking strength.

[0174] In Comparative Example 2, since polyethylene glycol was used to replace polyaniline, the synergistic conductive effect of polyaniline and carbon nanotubes could not be exerted, resulting in a decrease in antistatic performance and an increase in static voltage.

[0175] In Comparative Example 3, since silica as a carrier was omitted and carbon nanotubes coated with polyaniline were directly added to the oil agent, the thermal stability of the fiber decreased due to the lack of silica, and the breaking strength decreased significantly after high-temperature treatment. At the same time, it led to a decrease in the dispersion uniformity of the carbon nanotubes, and the carbon nanotubes were prone to sedimentation and aggregation in the oil agent, resulting in a decrease in the breaking strength of the fiber.

[0176] In summary, the static voltage of the ultra-high molecular weight polyethylene fiber treated with the said oil agent (containing the antistatic agent provided by the present invention) ≤0.041 kV, the initial modulus ≥1900 cN / dtex, the initial breaking strength ≥40.0 cN / dtex, and the decrease in the breaking strength under high-temperature conditions is small; after the fiber is placed in an oven at 200 °C and kept for 72 h and then taken out, the decrease in the breaking strength ≤9.2%.

[0177] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of an antistatic agent, characterized in that, The method comprises: firstly, modifying the carbon nanotubes with a silane coupling agent, wherein the siloxane groups and the functional groups on the surface of the carbon nanotubes form covalent bonds through a condensation reaction, thereby anchoring the carbon nanotubes on the surface; introducing flexible segments to provide sufficient steric hindrance, thereby avoiding direct contact between the carbon nanotubes and the effect of van der Waals forces; the modified carbon nanotubes are not easy to aggregate or re-aggregate, making it easier for them to interact with organic molecules in the oil, thereby improving the dispersibility of the carbon nanotubes in the oil; Then, the modified carbon nanotubes are coated with polyaniline. Polyaniline has good electrical conductivity and is rich in π electron systems like carbon nanotubes. The continuous electron transmission network formed by the π-π stacking interaction can effectively improve the overall electrical conductivity of the material. The carbon nanotubes provide fast electron transmission channels, and the electrical conductivity of polyaniline further enhances these channels. This enhanced electron transmission ability enables the charge to be quickly conducted on the surface or in the body of the material, thereby effectively dissipating static electricity accumulation and reducing the generation and accumulation of static electricity. Through the π-π interaction, the polyaniline molecular chain forms a uniform and continuous coating layer on the surface of the carbon nanotube as a physical barrier to prevent the oxidation of the carbon nanotube during processing or application. Finally, the modified carbon nanotubes coated with polyaniline are loaded on a silica carrier to obtain a finished SiO2-CNTs composite material, namely the antistatic agent; silica has excellent thermal stability and can maintain its physical and chemical properties unchanged under high temperature environment, thereby providing a stable base for the entire composite material; the surface roughness and pore structure of silica also help to physically embed or attach carbon nanotubes, reducing the sedimentation or aggregation of carbon nanotubes in the oil; The preparation method specifically comprises the following steps: S1: weighing or measuring carbon nanotubes and ethanol, adding the carbon nanotubes into the ethanol and performing ultrasonic dispersion to obtain a carbon nanotube solution; S2: taking a quantity of silane coupling agent and dissolving it in ethanol, slowly adding distilled water under stirring conditions, adjusting the pH value, and allowing the mixed solution to stand until the silane coupling agent is fully hydrolyzed to obtain a silane coupling agent solution; S3: slowly adding the carbon nanotube solution into the silane coupling agent solution and stirring, and obtaining a reaction mixture after the reaction is completed; S4: baking the reaction mixture, cooling it to room temperature and then vacuum drying it to obtain carbon nanotubes modified with a silane coupling agent; S5: ultrasonically dispersing the carbon nanotubes modified with the silane coupling agent in an aqueous solution and adding aniline, stirring and mixing the mixture thoroughly; cooling the mixture in an ice bath and adding an ammonium persulfate solution, stirring the mixture at 0°C, and after the reaction is completed, filtering, washing and drying the mixture to obtain the polyaniline-coated carbon nanotubes; S6: adding the polyaniline-coated carbon nanotubes to an aqueous solution containing sodium dodecylbenzene sulfonate, and subjecting the solution to ultrasonic treatment to obtain a carbon nanotube suspension; slowly adding silicon dioxide powder to the carbon nanotube suspension, stirring evenly, and heating and continuing to stir to obtain a composite semi-finished product; S7: drying and heat treating the semi-finished composite material, and after cooling, screening and washing to obtain a finished SiO2-CNTs composite material, i.e., the antistatic agent; In step S7, the specific operation of the heat treatment is to dry the composite material semi-finished product in the air, and then heat it to 500 ± 100 °C in a tubular furnace at a heating rate of 5 ± 1 °C / min, and the treatment time is 120 - 160 min.

2. The preparation method according to claim 1, characterized in that, In step S2, the volume ratio of the silane coupling agent to ethanol is 1:10 - 12; the volume ratio of the silane coupling agent to distilled water is 1:3 - 3.5; the pH value adjustment range is 4 - 5, and the standing time is ≥ 2 h; the silane coupling agent is KH-550 or KH-560.

3. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the silane coupling agent solution to the carbon nanotube solution is 0.2 - 0.4:1, and the stirring time is ≥ 4 hours.

4. The preparation method according to claim 1, characterized in that, The specific operation of step S4 is: transfer the reaction mixture to a constant temperature oven and keep it at 80 - 100 °C for 12 - 14 hours; after cooling to room temperature, dry the reaction mixture in a vacuum drying oven for 24 - 30 hours to obtain carbon nanotubes modified with a silane coupling agent.

5. The preparation method according to claim 1, characterized in that, In step S5, the mass ratio of the carbon nanotubes modified with a silane coupling agent to aniline is 1:6 - 10; the mass ratio of ammonium persulfate to aniline is 0.05 - 0.1:1, and the reaction time is 4 - 6 hours.

6. The preparation method according to claim 1, characterized in that, In step S6, the mass concentration of the sodium dodecylbenzenesulfonate aqueous solution is 1 - 1.2%, the volume ratio of the carbon nanotubes coated with polyaniline to the sodium dodecylbenzenesulfonate aqueous solution is 1:400 - 500; the mass ratio of the silicon dioxide powder to the carbon nanotubes coated with polyaniline is 8 - 15:1, the heating temperature is 80 °C - 100 °C, and the reaction time is ≥ 3 hours.

7. An antistatic agent, characterized in that, The antistatic agent is prepared by the preparation method according to any one of claims 1 - 6.

8. An oil agent for ultra-high molecular weight polyethylene fibers, characterized in that, The sizing agent includes the antistatic agent according to claim 7.

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