A track anti-stray current solventless insulating elastomeric coating and a method of making the same

Abstract

This application discloses a solvent-free insulating elastic coating for preventing stray currents in railway tracks and its preparation method, belonging to the field of functional coating technology. The coating comprises component A and component B. By mass, component A includes 35-55 parts of polyaspartic acid ester, 5-10 parts of aminoalkoxysilane, 3-10 parts of insulating-treated iron(III) oxide, 0.2-1 parts of modified polyimide nanofibers, 30-50 parts of functional filler, 0.1-0.3 parts of thickener, 0.2-0.5 parts of wetting and dispersing agent, 0.1-0.4 parts of defoamer, and 0.1-0.3 parts of leveling agent; component B includes 25-35 parts of aliphatic isocyanate trimer; the mass ratio of component A to component B is 100:(20-30). The coating provided in this application has excellent fast-drying, thick-film, insulating, superhydrophobic and oleophobic properties, high elasticity, good adhesion, and no VOCs. It can meet the requirements of subway tracks for long-term effective insulation and stray current prevention, as well as the requirements of short construction time during the window period and no pollution in enclosed spaces.

Description

Technical Field

[0001] This invention belongs to the field of functional coatings technology, specifically relating to a solvent-free insulating elastic coating for railway tracks that prevents stray currents and its preparation method. Background Technology

[0002] Modern trams and subways primarily use DC 1500V or DC 750V traction networks for power supply, typically achieved through overhead contact lines. This means the substation supplies power to the train via the contact line or conductive rails, and the current returns to the substation via the contact line, locomotive, and rails, forming a circuit. However, due to poor or damaged insulation between the rails and the track bed, some current can leak through unexpected paths such as the track bed and structural reinforcement, creating stray currents. These currents not only accelerate the electrochemical corrosion of the tracks and surrounding metal structures but can also cause abnormal increases in rail potential, leading to Class A accidents such as arcing and discharge in trackside equipment (e.g., air-raid shelter doors, switch machines), and in severe cases, even endangering personal safety.

[0003] To address the issue of stray current diffusion, existing technologies include three-layer polyethylene coating systems, two-layer epoxy coating systems, and single-layer composite coating systems. While multi-layer systems can meet the requirements for thick films, they suffer from complex application processes, are generally unsuitable for on-site coating, and are difficult to repair after coating damage. Existing single-layer coatings, although easy to apply, have relatively thin films and are limited by material formulations, making it difficult to balance abrasion resistance, flexibility, corrosion resistance, and adhesion. They are often adjusted according to actual construction needs. For example, on sections of road where traffic is smooth with minimal vibration and impact, the coating prioritizes abrasion resistance while sacrificing some flexibility; on bumpier sections, to prevent cracking and peeling, the coating prioritizes high adhesion and flexibility, sacrificing some abrasion resistance. Furthermore, existing coatings often use solvents for formulation, containing volatile gases such as VOCs, which can be harmful to human health when applied in enclosed environments.

[0004] Therefore, there is an urgent need to develop a protective coating with high adhesion, fast drying, thick film, high insulation, high abrasion resistance, superhydrophobicity, oleophobicity, and elasticity to meet the needs of protecting against stray currents and to have a wide range of applications. Summary of the Invention

[0005] Therefore, the purpose of this application is to provide a solvent-free insulating elastic coating for preventing stray currents in railway tracks and its preparation method, to solve the problems of existing single-layer coatings having generally poor performance, slow drying speed, and inability to simultaneously meet the requirements of insulation, high adhesion, wear resistance, and high elasticity. Furthermore, the coating provided in this application is VOC-free, environmentally friendly, and has excellent hydrophobic and oleophobic properties, good durability, and corrosion resistance. Even after long-term use, it maintains excellent insulation, wear resistance, and flexibility, meeting the long-term stray current prevention requirements of subway or tram tracks. It also avoids the phenomenon of decreased coating insulation performance due to surface contamination during use, resulting in high economic value and broad application prospects.

[0006] The embodiments of this application are implemented as follows: A solvent-free insulating elastic coating for track use to prevent stray currents, comprising component A and component B. By weight, component A comprises 35-55 parts polyaspartic acid ester, 5-10 parts aminoalkoxysilane, 3-10 parts insulated iron oxide, 0.2-1 parts modified polyimide nanofibers, 30-50 parts functional filler, 0.1-0.3 parts thickener, 0.2-0.5 parts wetting and dispersing agent, 0.1-0.4 parts defoamer, and 0.1-0.3 parts leveling agent; component B comprises 25-35 parts aliphatic isocyanate trimer.

[0007] Furthermore, the method for preparing the insulating-treated iron(III) oxide includes the following steps: S1. Place the pretreated iron oxide powder in a mixed solution of ethanol and water, and disperse it evenly by ultrasonication; add ammonia to adjust the pH value to 9-10; and prepare a suspension. S2. Mix tetraethyl orthosilicate with an appropriate amount of ethanol solution to prepare a mixed solution; S3. While continuously stirring, heat the suspension to 25-35°C, slowly add the mixed solution dropwise into it, and continue stirring the reaction for 8-12 hours after the addition is complete. S4. Collect solid particles, wash them sequentially with ethanol and deionized water, and then vacuum dry them.

[0008] Furthermore, the preparation method of the pretreated iron oxide powder in step S1 includes the following steps: S11. Acid washing treatment of iron oxide powder; S12. Disperse the acid-washed powder in anhydrous ethanol solution to form a ferric oxide / ethanol suspension; place γ-aminopropyltriethoxysilane in another part of anhydrous ethanol solution, adjust the solution to acidity, add deionized water, and then sonicate to form a hydrolysate. S13. Keep the iron oxide / ethanol suspension stirred, and slowly add the hydrolysate dropwise under nitrogen protection. Reflux at 60-80°C for 4-6 hours. After cooling to room temperature, magnetically separate the solid product, wash with anhydrous ethanol, and vacuum dry.

[0009] Furthermore, the acid washing treatment of the iron oxide powder in step S11 includes: Ferric oxide powder is immersed in dilute nitric acid or dilute hydrochloric acid solution, and a solid is obtained by magnetic separation. The solid is then washed alternately with deionized water and ethanol until the washing solution is neutral.

[0010] Furthermore, the preparation method of the modified polyimide nanofibers includes the following steps: S1. Immerse polyimide nanofibers in potassium hydroxide solution and stir at 60-80°C for 0.5-2 hours; cool to room temperature, wash with deionized water until neutral, and vacuum dry; S2. Place it in anhydrous ethanol solution, stir thoroughly, adjust the pH to 4-5, heat to 70-80℃, add γ-aminopropyltriethoxysilane solution, and reflux for 6-10 hours. S3. Wash repeatedly with anhydrous ethanol solution until the washing solution is neutral, then vacuum dry.

[0011] Furthermore, the functional filler includes titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder.

[0012] Furthermore, the mass ratio of the titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder is 3:1:5:1.

[0013] Furthermore, the thickener is BYK430; the wetting and dispersing agent is BYK220S; the defoamer is BYK1790; and the leveling agent is EFKA3600.

[0014] Furthermore, the mass ratio of component A to component B is 100:(20-30).

[0015] This application also provides a method for preparing a stray current-preventing insulating coating for railway tracks, comprising the following steps: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 30-40℃, and stir and disperse at 600-900 rpm for 3-5 min; slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1000-1500 rpm for 30-40 min; then ultrasonically stir and disperse under ice-water bath conditions for 15-30 min; S2. Heat to room temperature, reduce the rotation speed by 600-900 rpm, slowly add Fe3O4@SiO2, and after the addition is complete, stir and disperse at 1000-1500 rpm for 15-30 min; then, under ice-water bath conditions, ultrasonically stir and disperse for 10-15 min. S3. Heat to room temperature, reduce the rotation speed by 300-500 rpm, slowly add the functional filler, and after the addition is complete, stir and disperse at 1000-1500 rpm for 10-15 minutes; then reduce the rotation speed to 300-500 rpm, add the thickener and leveling agent in sequence, and stir at 1000-1500 rpm for 10-15 minutes. S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir for 10-15 minutes at 1000-1500 rpm. Filter and dispense to obtain ingredient A. S5. Add the aliphatic isocyanate trimer to a dispersion tank, stir and disperse at 600-900 rpm for 5-8 min, filter and dispense to obtain ingredient B; S6. Mix ingredients A and B together and stir until homogeneous to obtain a track-proof stray current insulating coating.

[0016] Compared with the prior art, the beneficial effects of this application are: 1. Polyaspartic acid ester resin and aminoalkoxysilane form an IPN interpenetrating network structure, further enhancing the coating's corrosion resistance. This provides improved mechanical properties in both static and dynamic (vibration-induced) environments. Furthermore, the aminoalkoxysilane undergoes hydrolysis with airborne moisture, creating a silicon-oxygen-silicon network structure with microscopic roughness and low surface energy on the coating surface, achieving superhydrophobic and oleophobic properties. The aminoalkoxysilane is anchored within the resin system by chemical bonds with insulating iron oxide, modified polyimide nanofibers, mica, and other fillers. This creates a molecular-level three-dimensional chemical bond network within the resin, between the resin and fillers, and between the resin and the substrate, reducing stress concentration points and further improving the coating's wear resistance, impact resistance, and mechanical strength. This results in excellent properties such as high strength, high adhesion, and long service life.

[0017] 2. Using insulated iron oxide (Fe3O4) not only utilizes its magnetic attraction properties to resist the shrinkage stress of the coating, reducing microcracks caused by curing shrinkage and significantly improving the coating's toughness, but also significantly enhances the coating's adhesion and peel resistance; especially in environments with large temperature variations or frequent stress deformation, it can provide additional bonding strength.

[0018] 3. The addition of modified polyimide nanofibers to the coating, used in conjunction with polyaspartic acid ester resin, produces a synergistic effect greater than the sum of its parts (1+1>2). Polyimide nanofibers are stable and have good heat resistance; they do not decompose or soften during coating curing, significantly improving the coating's toughness and wear resistance, making it more impact-resistant and crack-resistant. They also enhance the coating's hardness and dimensional stability, making it more wear-resistant and deformation-resistant; furthermore, they impart better thermal stability to the coating.

[0019] 4. The coating provided in this application is a solvent-free, thick-film, fast-drying product with a single-coat thickness of over 300μm and a drying time of ≤20 minutes. It meets the requirements of short construction periods for railway track windows, offering high economic value and broad application prospects. Furthermore, it is VOC-free, making it ideal for enclosed operations and minimizing environmental hazards. Its elongation at break is ≥200%, meeting the needs of equipment and facilities subject to continuous vibration. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. The illustrative embodiments and descriptions of this application are for explanation only and are not intended to limit the scope of this application. Any product identical or similar to this application, derived by any person based on the teachings of this application or by combining features of this application with other prior art, falls within the protection scope of this application.

[0021] For any experimental steps or conditions not specified in the examples, the procedures or conditions described in the conventional experimental procedures in the art can be followed. Reagents and other instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0022] Explanation of proper nouns: BYK220S: A commercially available wetting and dispersing agent manufactured by BYK GmbH, Germany; primarily used in solvent-based and solvent-free coatings, as well as room-temperature curing plastic systems (such as unsaturated polyester resins, gel coats, acrylics, polyurethanes, and epoxy resins), it stabilizes pigment dispersion, improves floating color and blooming phenomena, reduces filler settling, and enhances surface smoothness and leveling.

[0023] BYK430: A commercially available thickener manufactured by BYK GmbH, Germany; primarily used in medium-polarity solvent-based and solvent-free systems, such as solvent-based coatings, adhesives, and sealants.

[0024] EFKA3600: A commercially available leveling agent manufactured by BASF in Germany; its main function is to reduce the surface tension of various organic coating systems. As an anti-cratering agent and flow control aid, it can effectively improve the wettability, leveling and surface smoothness of coatings.

[0025] BYK1790: A commercially available defoamer manufactured by BYK GmbH, Germany; suitable for thick coating applications and high viscosity systems, effectively solving problems such as reduced system density, impact on mechanical properties, and surface defects caused by foam formation.

[0026] This application provides a solvent-free insulating elastic coating for railway tracks to prevent stray currents, comprising component A and component B, wherein component A is specifically as follows: The product comprises 35 to 55 parts by weight of polyaspartic acid ester resin, preferably with a solid content of not less than 100% and an NH equivalent of 200 to 300 g / mol.

[0027] 5 to 10 parts of aminoalkoxysilane, further comprising at least one of aminopropyltrimethoxysilane and aminopropyltriethoxysilane.

[0028] During the film formation process of the coating, aminoalkoxysilanes gradually migrate to the coating surface. During the use of the coating, they gradually undergo hydrolysis with water vapor in the air to produce silanols (-Si-OH) with active groups. The silanols further condense to form siloxanes, which form an organic-inorganic hybrid network interpenetrating structure with the polyaspartic acid ester resin system. This results in an enriched silicon-oxygen-silicon network structure with microscopic roughness and low surface energy on the coating surface, exhibiting the superhydrophobic and oleophobic properties of the coating.

[0029] 3 to 10 parts of insulated iron(III) oxide.

[0030] Fe exists simultaneously in the iron oxide lattice. 2+ and Fe 3+ While conductive, iron oxide (Fe3O4) is generally unsuitable for insulating coatings. Even when used, it is only applicable to certain coating systems and requires strict dosage control. The applicant has creatively insulated iron oxide, enabling its unrestricted use in insulating coating systems, and ensuring easy compatibility with the base resin. The insulated iron oxide is non-conductive, meeting the insulation requirements of the coating, while retaining its permanent magnetism. This effectively resists shrinkage stress in the coating, reduces microcracks caused by curing shrinkage, and significantly improves the coating's toughness. When used on metal pipes, it significantly enhances coating adhesion and peel resistance; especially in environments with large temperature variations or frequent deformation, it provides additional bonding strength. Furthermore, due to its magnetism, workers can use a magnetometer or magnetic probe to quickly scan the coating, locating damage points based on magnetic anomalies, greatly facilitating non-contact coating inspection and maintenance.

[0031] The method for preparing insulating iron(III) oxide is as follows: S1. Place the pretreated iron oxide powder in a mixed solution of ethanol and water, and disperse it by ultrasonication to make it evenly distributed, forming a reaction system; mix tetraethyl orthosilicate with an appropriate amount of ethanol solution evenly to form a TEOS-ethanol mixed solution for later use. S2. Add ammonia to the reaction system, adjust the pH to 9-10, and continue stirring; S3. Keep the reaction system under continuous and uniform stirring, heat to 25-35℃, slowly add the TEOS-ethanol mixed solution dropwise to the reaction system, and continue stirring and react for 8-12 hours after the addition is complete. S4. After the reaction is complete, collect the solid particles, wash them with ethanol and deionized water in sequence, and then vacuum dry them to obtain Fe3O4@SiO2 powder coated with a silica shell.

[0032] Furthermore, the pretreatment process for the iron oxide powder in step S1 is as follows: S11. Pickling treatment: Soak the iron oxide powder briefly in dilute nitric acid or dilute hydrochloric acid, and after separation, wash with deionized water and ethanol alternately until the washing solution is neutral.

[0033] This treatment effectively cleans the surface of the iron oxide powder, increases the surface hydroxyl density, and reduces powder agglomeration.

[0034] S12. Silane Coupling Agent Modification: First, the acid-washed iron(III) oxide powder is dispersed in anhydrous ethanol solution and stirred for later use to form an iron(III) oxide / ethanol suspension. γ-aminopropyltriethoxysilane is placed in another portion of anhydrous ethanol solution, the solution is adjusted to acidity, a small amount of deionized water is added, and the mixture is ultrasonically stirred to hydrolyze the γ-aminopropyltriethoxysilane, forming a hydrolysate. While maintaining the iron(III) oxide / ethanol suspension under stirring, the hydrolysate is slowly added dropwise under nitrogen protection, and the mixture is refluxed at 60–80°C for 4–6 hours. After cooling to room temperature, the solid product is magnetically separated, repeatedly washed with anhydrous ethanol, and vacuum dried to obtain surface-silanized iron(III) oxide powder.

[0035] By modifying iron oxide with a silane coupling agent, -Si-OH groups were grafted onto the surface of iron oxide powder. The -Si-OH groups served as active sites for subsequent SiO2 growth, promoting the growth of silicon dioxide on the iron oxide surface and reducing the occurrence of silicon dioxide nucleation growth on its own.

[0036] In addition, the iron oxide powder is preferably nano iron oxide powder, and the particle size is preferably 100-200 nanometers.

[0037] In step S3, the TEOS-ethanol mixed solution is added to the reaction system at a very slow rate, which promotes the growth of silica into a silica shell on the surface of the iron oxide powder, thus avoiding the self-nucleation of silica.

[0038] Based on this, a Fe3O4@SiO2 core-shell structure was obtained, with Fe3O4 as the core and SiO2 as the outer shell.

[0039] 0.2 to 1 part of modified polyimide nanofibers, further wherein the length of the modified polyimide nanofibers is preferably 5 to 50 μm and the diameter is preferably 50 to 200 nm.

[0040] The method for preparing polyimide nanofibers can refer to existing technologies, such as Chinese patent CN110106635B, etc., and will not be elaborated here. After purchasing or making the polyimide nanofibers, modification treatment is performed, including the following steps: S1. Immerse polyimide nanofibers in potassium hydroxide solution and stir at 60-80°C for 0.5-2 hours; then cool to room temperature, wash repeatedly with deionized water until neutral, and vacuum dry; S2. Place it in anhydrous ethanol solution and stir thoroughly to disperse it evenly; then add hydrochloric acid to adjust the pH to 4-5, heat to 70-80℃, add γ-aminopropyltriethoxysilane solution and reflux for 6-10 hours; then wash repeatedly with anhydrous ethanol solution and vacuum dry.

[0041] The modified polyimide nanofibers have -NH2 groups on their surface, which react with -NCO groups in the curing agent to form strong covalent bonds; thus, they are effectively combined with the matrix resin, significantly playing a reinforcing role.

[0042] Modified polyimide nanofibers, when used in combination with polyaspartic acid ester resin and isocyanate curing agents, produce a synergistic effect greater than the sum of its parts (1+1>2). The polar groups, such as the carbonyl groups, on the polyimide molecular chain form dense and strong dipole-dipole interactions and hydrogen bonds (C=O…HN) with the NH and C=O bonds of the urea and urethane bonds in the cured network, exhibiting strong attraction at the molecular level and achieving robust interfacial bonding and stress transfer. Furthermore, the polyimide molecular chain is not easily coiled; during curing, the rigid segments of the nanofibers can locally restrict the movement of nearby resin molecules and form slight topological entanglements, creating a microscopic "semi-interpenetrating network" structure. This not only improves the coating's modulus and heat resistance but also enhances its toughness under external forces through energy dissipation mechanisms between the rigid fibers and the flexible resin network (such as interfacial friction and micro-area shear yielding), thus improving the coating's crack resistance.

[0043] Furthermore, polyimide nanofibers are highly stable and heat-resistant. They do not decompose or soften when cured with polyaspartic acid ester resin at room temperature or high temperatures, maintaining their structure and properties. This significantly improves the toughness and wear resistance of the coating, making it more impact-resistant and crack-resistant. This is because polyimide nanofibers have high tensile strength and modulus, and are nano-sized. Their uniform dispersion within the polyaspartic acid ester resin effectively transfers and disperses stress, preventing the generation and propagation of microcracks, resulting in excellent toughness. They also enhance the coating's hardness and dimensional stability, making it more wear-resistant and deformation-resistant, and imparting superior thermal stability. In practical applications, stray current-induced thermal effects and frictional heat can easily damage the coating and shorten its lifespan. However, the combination of polyimide nanofibers and polyaspartic acid ester resin exhibits excellent heat resistance, allowing the coating to maintain its properties even at high temperatures, resisting aging and extending its service life.

[0044] 30-50 parts of functional filler, specifically, the functional filler includes titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder. Further, the preferred mass ratio of titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder is 3:1:5:1.

[0045] 0.1–0.3 parts thickener, preferably BYK 430. 0.2–0.5 parts wetting and dispersing agent, preferably BYK 220S. 0.1–0.4 parts defoamer, preferably BYK 1790. 0.1–0.3 parts leveling agent, preferably EFKA 3600.

[0046] Component B is specifically a polyisocyanate curing agent, preferably an aliphatic isocyanate trimer. Its dosage is 25–35 parts by weight.

[0047] The preferred mass ratio of component A to component B is 100:(20-30). That is, component A is prepared by dispensing to obtain component A, and component B is prepared to form component B. By mass, 100 parts of component A and 20-30 parts of component B are mixed and stirred evenly to obtain the track-resistant stray current insulating coating provided in this application.

[0048] This application also provides a method for preparing a track-grade anti-stray current insulating coating, the specific steps of which are as follows: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 30-40℃, and stir and disperse at 600-900 rpm for 3-5 min; then slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1000-1500 rpm for 30-40 min; then ultrasonically stir and disperse under ice-water bath conditions for 15-30 min; so that the modified polyimide nanofibers are fully and uniformly dispersed in the coating slurry.

[0049] S2. Heat to room temperature, reduce the rotation speed by 600-900 rpm, and slowly add Fe3O4@SiO2. After the addition is complete, stir and disperse at 1000-1500 rpm for 15-30 minutes. Then, under ice-water bath conditions, ultrasonically stir and disperse for 10-15 minutes to ensure that Fe3O4@SiO2 is fully and uniformly dispersed in the coating slurry.

[0050] S3. Heat to room temperature, reduce the rotation speed by 300-500 rpm, slowly add the functional filler, and after adding, stir and disperse at 1000-1500 rpm for 10-15 minutes; then reduce the rotation speed to 300-500 rpm, add the thickener and leveling agent in sequence, and stir at 1000-1500 rpm for 10-15 minutes.

[0051] S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1000-1500rpm for 10-15min. Filter and package to obtain ingredient A.

[0052] S5. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 600-900 rpm for 5-8 minutes, filter and dispense to obtain ingredient B.

[0053] S6. By weight, take 100 parts of ingredient A and 20-30 parts of ingredient B, mix them, and stir evenly to obtain the track-proof stray current insulating coating.

[0054] It should be noted that ingredient A and ingredient B will solidify within a certain time after mixing, therefore they should be applied and used as soon as possible after mixing. Therefore, the method for preparing a solvent-free insulating elastic coating for preventing stray currents in railway tracks provided in this application is applicable to specific construction sites, or ingredient A and ingredient B can be prepared in advance and mixed evenly at the construction site for use. At non-construction sites, please avoid mixing ingredient A and ingredient B to prevent premature curing of the coating and subsequent material waste.

[0055] Based on the applicant's original preparation method, modified polyimide nanofibers and insulated iron oxide can be uniformly dispersed in the resin crosslinking network, and also play a physical reinforcing role, which can improve the density, hardness, rigidity and wear resistance of the coating, and effectively delay the occurrence of coating wear or damage.

[0056] The solvent-free insulating elastic coating for track use, designed to prevent stray currents, provided in this application is suitable for various application methods, including brushing and spraying. After application, it dries in approximately 15 minutes at room temperature. Using this coating, an insulating, abrasion-resistant, elastic, and superhydrophobic / oleophobic protective coating is formed. Testing shows it withstands damp heat and salt spray for over 1000 hours; maintains aging resistance for over 3000 hours; has a flexibility of 1mm; has an elongation at break ≥200%; exhibits abrasion resistance of 1000g / 1000r and a resistivity of 45mg or less; and has a volume resistivity greater than 5.5×10⁻⁶. 13 Ω·m and above; adhesion of 15MPa and above; in terms of hydrophobicity, the water contact angle is ≥160° and the roll-off angle is ≤3°; in terms of oleophobicity, the oil (n-hexadecane) contact angle is ≥150°.

[0057] The following will further describe and illustrate the insulating, wear-resistant, superhydrophobic, and oleophobic coating for railways provided in this application through examples and test cases.

[0058] Example 1: Prepare raw materials according to the formula and dosage shown in Table 1 below: Table 1: Raw Material Formula Table

[0059] Mix component A to form ingredient A, mix component B to form ingredient B, and then prepare the coating by following these steps: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 30℃, stir and disperse at 600 rpm for 5 min; then slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1000 rpm for 40 min; then ultrasonically stir and disperse under ice water bath conditions for 20 min.

[0060] S2. Heat to room temperature, reduce the rotation speed by 600 rpm, slowly add Fe3O4@SiO2, and after the addition is complete, stir and disperse at 1000 rpm for 30 min; then, under ice-water bath conditions, ultrasonically stir and disperse for 15 min.

[0061] S3. Heat to room temperature, reduce the rotation speed by 300 rpm, and add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence. After adding, stir and disperse at 1000 rpm for 10 minutes. Then reduce the rotation speed to 300 rpm, add thickener and leveling agent in sequence, and stir at 1000 rpm for 10 minutes.

[0062] S4. Transfer the material into a sand mill for grinding until the fineness is <40μm. Then add defoamer and stir at 1000rpm for 10min. Filter and package to obtain ingredient A.

[0063] S5. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 600 rpm for 8 min, filter and dispense to obtain ingredient B.

[0064] S6. By weight, take 100 parts of ingredient A and 25 parts of ingredient B, mix them, and stir evenly to obtain the track-proof stray current insulating coating.

[0065] Example 2: Prepare raw materials according to the formula and dosage shown in Table 2 below: Table 2: Raw Material Formula Table

[0066] Mix component A to form ingredient A, mix component B to form ingredient B, and then prepare the coating by following these steps: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 40℃, stir and disperse at 900 rpm for 3 min; then slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1500 rpm for 30 min; then ultrasonically stir and disperse under ice water bath conditions for 15 min.

[0067] S2. Heat to room temperature, reduce the rotation speed by 900 rpm, slowly add Fe3O4@SiO2, and after the addition is complete, stir and disperse at 1500 rpm for 15 min; then, under ice-water bath conditions, ultrasonically stir and disperse for 10 min.

[0068] S3. Heat to room temperature, reduce the rotation speed by 500 rpm, and add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence. After adding all the ingredients, stir and disperse at 1500 rpm for 15 minutes. Then reduce the rotation speed to 500 rpm, add thickener and leveling agent in sequence, and stir at 1500 rpm for 15 minutes.

[0069] S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1500rpm for 15min. Filter and package to obtain ingredient A.

[0070] S5. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 900 rpm for 5 min, filter and dispense to obtain ingredient B.

[0071] S6. By weight, take 100 parts of ingredient A and 20 parts of ingredient B, mix them, and stir evenly to obtain the track-proof stray current insulating coating.

[0072] Example 3: Prepare raw materials according to the formula and dosage shown in Table 3 below: Table 3: Raw Material Formula Table

[0073] Mix component A to form ingredient A, mix component B to form ingredient B, and then prepare the coating by following these steps: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 35℃, and stir and disperse at 800 rpm for 4 min; then slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1300 rpm for 40 min; then ultrasonically stir and disperse under ice-water bath conditions for 30 min.

[0074] S2. Heat to room temperature, reduce the rotation speed by 800 rpm, slowly add Fe3O4@SiO2, and after the addition is complete, stir and disperse at 1300 rpm for 25 min; then, under ice-water bath conditions, ultrasonically stir and disperse for 12 min.

[0075] S3. Heat to room temperature, reduce the rotation speed by 400 rpm, and add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence. After the addition is complete, stir and disperse at 1300 rpm for 12 minutes. Then reduce the rotation speed to 400 rpm, add thickener and leveling agent in sequence, and stir at 1300 rpm for 12 minutes.

[0076] S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1300rpm for 12min. Filter and package to obtain ingredient A.

[0077] S5. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 800 rpm for 7 min, filter and dispense to obtain ingredient B.

[0078] S6. By weight, take 100 parts of ingredient A and 30 parts of ingredient B, mix them, and stir evenly to obtain the track-proof stray current insulating coating.

[0079] Example 4: Prepare raw materials according to the formula and dosage shown in Table 4 below: Table 4: Raw Material Formula Table

[0080] A comparison of Table 4 and Table 1 shows that the raw materials used in Example 4 differ from those used in Example 1 only in the amount of reinforcing filler Fe3O4@SiO2. All other raw materials and their amounts remain the same.

[0081] The coating was prepared according to the method and steps of Example 1, with all relevant parameters maintained throughout the process. A track-grade anti-stray current insulating coating was thus obtained.

[0082] Example 5: Prepare raw materials according to the formula and dosage shown in Table 5 below: Table 5: Raw Material Formula Table

[0083] A comparison of Tables 5 and 3 shows that the raw materials used in Example 5 differ from those used in Example 3 only in the amount of the reinforcing filler-modified polyimide nanofibers. All other raw materials and their amounts remain the same.

[0084] The coating was prepared according to the method and steps of Example 3, with all relevant parameters maintained throughout the process. A track-grade anti-stray current insulating coating was thus obtained.

[0085] Comparative Example 1: Comparative Example 1 prepared a coating using the same raw materials and methods as in Example 3, except that Fe3O4@SiO2 was not used. The other raw materials and their amounts were the same as in Example 3.

[0086] The preparation method omits the step for adding Fe3O4@SiO2, specifically: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 35℃, and stir and disperse at 800 rpm for 4 min; then slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1300 rpm for 40 min; then ultrasonically stir and disperse under ice-water bath conditions for 30 min.

[0087] S2. Heat to room temperature, reduce the rotation speed by 400 rpm, and add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence. After the addition is complete, stir and disperse at 1300 rpm for 12 minutes. Then reduce the rotation speed to 400 rpm, add thickener and leveling agent in sequence, and stir at 1300 rpm for 12 minutes.

[0088] S3. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1300rpm for 12min. Filter and package to obtain ingredient A.

[0089] S4. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 800 rpm for 7 min, filter and dispense to obtain ingredient B.

[0090] S5. By weight, take 100 parts of ingredient A and 30 parts of ingredient B, mix them, and stir evenly to obtain the coating.

[0091] Comparative Example 2: Comparative Example 2 prepared a coating using the same raw materials and methods as in Example 3, except that modified polyimide nanofibers were not used. The other raw materials and their amounts were the same as in Example 3.

[0092] The preparation method omits the step of preparing for the addition of modified polyimide nanofibers, specifically: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 35℃, and stir and disperse at 800 rpm for 4 min.

[0093] S2. Keep the rotation speed constant and slowly add Fe3O4@SiO2. After the addition is complete, stir and disperse at 1300 rpm for 25 min; then, ultrasonically stir and disperse under ice-water bath conditions for 12 min.

[0094] S3. Heat to room temperature, reduce the rotation speed by 400 rpm, and add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence. After the addition is complete, stir and disperse at 1300 rpm for 12 minutes. Then reduce the rotation speed to 400 rpm, add thickener and leveling agent in sequence, and stir at 1300 rpm for 12 minutes.

[0095] S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1300rpm for 12min. Filter and package to obtain ingredient A.

[0096] S5. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 800 rpm for 7 min, filter and dispense to obtain ingredient B.

[0097] S6. By weight, take 100 parts of ingredient A and 30 parts of ingredient B, mix them, and stir evenly to obtain the coating.

[0098] Comparative Example 3: Comparative Example 2 prepared a coating using the same raw materials and methods as in Example 3, except that Fe3O4@SiO2 and modified polyimide nanofibers were not used. The other raw materials and their amounts were the same as in Example 3.

[0099] The preparation method omits the step of adding Fe3O4@SiO2 and modified polyimide nanofibers, specifically: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 35℃, and stir and disperse at 800 rpm for 4 min.

[0100] S2. Reduce the rotation speed to 400 rpm, add titanium dioxide powder, aluminum oxide powder, mica powder and hollow microspheres in sequence, and stir and disperse at 1300 rpm for 12 min after the addition is complete; then reduce the rotation speed to 400 rpm, add thickener and leveling agent in sequence, and stir at 1300 rpm for 12 min.

[0101] S3. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir at 1300rpm for 12min. Filter and package to obtain ingredient A.

[0102] S4. Add the aliphatic isocyanate trimer curing agent to the dispersion tank, stir and disperse at 800 rpm for 7 min, filter and dispense to obtain ingredient B.

[0103] S5. By weight, take 100 parts of ingredient A and 30 parts of ingredient B, mix them, and stir evenly to obtain the coating.

[0104] Test Example 1: The coatings obtained in Examples 1-5 and Comparative Examples 1-3 were uniformly applied to identical substrates meeting the same testing standards using air spraying, forming a 200 μm / coat thickness. The resulting coatings were tested using the following testing standards or methods: GB / T 1728 Determination of drying time of paint film and putty film; GB / T 9751 Determination of viscosity of coatings at high shear rates; GB / T 1731-1993 "Determination of Flexibility of Paint Films"; GB / T 23986-2009 "Determination of Volatile Organic Compounds in Coatings and Varnishes - Part 2: Gas Chromatography"; GB / T 5210 Paints and varnishes—Pull-off adhesion test; GB / T 528 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber; GB / T 1768 Paints and varnishes—Determination of abrasion resistance—Rotating rubber wheel method; GB / T 31838.2 Solid insulating materials—Dielectric and resistive properties—Part 2: Resistive properties (DC method)—Volume resistivity and volume resistivity; GB / T 1408.1 Electrical strength test methods for insulating materials - Part 1: Tests at power frequency; GB / T 1740 Test method for resistance to damp heat of paint film; GB / T 10125 Artificial Atmosphere Corrosion Tests - Salt Spray Test; GB / T 1865 Paints and varnishes - Artificial weathering and artificial radiation exposure (filtered xenon arc radiation); GB / T 26490-2011 Test method for superhydrophobic properties of nanomaterials.

[0105] The test indicators include conventional properties, mechanical properties, insulation properties, corrosion resistance, hydrophobic properties, and oleophobic properties. The test results are shown in Table 6 below.

[0106] Table 6 Summary of test results for coatings prepared in Examples 1-5 and Comparative Examples 1-3

[0107] The test results in Table 6 are analyzed below: First, all coatings provided in this application have an actual drying time of less than 15 minutes, exhibiting thick-film fast-drying characteristics, which can meet the needs of rapid construction. Furthermore, they do not contain VOCs, making them more environmentally friendly and meeting the requirement that construction in a closed environment will not harm human health.

[0108] Secondly, the coating made from the paint provided in this application has a volume resistivity of 7.3 × 10⁻⁶. 13 Ω•m or higher, dielectric strength above 35kV / mm; optimal volume resistivity 6.8×10 14 The coating exhibits excellent insulation properties, with a dielectric strength of 55 kV / mm and a small variance between the optimal and worst values, all meeting coating testing requirements. Furthermore, it demonstrates superior resistance to damp heat and salt spray (over 1000 hours) and aging (over 3000 hours). Its long service life and high market application value make it highly valuable.

[0109] As can be seen from the table, the coatings provided in Examples 1-5 all exhibit an elongation at break of over 205%, with the best reaching 230%; and a flexibility of 1 mm. This demonstrates that the coatings provided in this application possess excellent toughness and elasticity, good resistance to deformation, and can meet the requirements of not cracking or breaking under vibration. Furthermore, a comparison of the data from the examples and comparative examples (Example 3 has the highest elongation at break, while Comparative Examples 2 and 3 have relatively low elongation at break, ranging from 125-135) proves that the modified polyimide nanofibers significantly enhance the toughness and elasticity of the coatings. The coatings provided in Examples 1-5 all exhibit an adhesion strength of over 15, indicating strong adhesion; while the coatings provided in Comparative Examples 1 and 3 have adhesion strengths of 12 and 11 respectively, slightly weaker than the coatings provided in the examples, demonstrating that Fe3O4@SiO2 enhances the adhesion of the coatings. The coatings provided in Examples 1-5 all exhibit a wear resistance of below 42, demonstrating excellent wear resistance. Furthermore, based on a comprehensive comparison of the data from the examples and comparative examples, the Fe3O4@SiO2 and modified polyimide nanofibers in the formulation of this application both have a positive effect on improving the wear resistance of the coating.

[0110] Furthermore, regarding hydrophobicity, the highest water contact angle reaches 170°, and in all the test results provided in the embodiments, the water contact angle is ≥160°, proving that the coating provided in this application has a superhydrophobic effect. Simultaneously, the roll-off angle is less than 3°, further demonstrating that the coating provided in this application, in addition to excellent hydrophobicity, also possesses excellent self-cleaning properties. Surface dirt can be removed with rinsing, which is extremely valuable in practical applications and can significantly reduce subsequent maintenance costs. Regarding oleophobicity, the coatings provided in all embodiments achieve an oil (n-hexadecane) contact angle ≥150°, proving that the coating provided in this application has a superoleophobic effect.

[0111] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solvent-free insulating elastic coating for preventing stray currents in railway tracks, comprising component A and component B, characterized in that, By weight, component A comprises 35–55 parts polyaspartic acid ester, 5–10 parts aminoalkoxysilane, 3–10 parts insulated iron oxide, 0.2–1 part modified polyimide nanofibers, 30–50 parts functional filler, 0.1–0.3 parts thickener, 0.2–0.5 parts wetting and dispersing agent, 0.1–0.4 parts defoamer, and 0.1–0.3 parts leveling agent; component B comprises 25–35 parts aliphatic isocyanate trimer.

2. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 1, characterized in that, The method for preparing the insulating iron oxide includes the following steps: S1. Place the pretreated iron oxide powder in a mixed solution of ethanol and water, and disperse it evenly by ultrasonication; add ammonia to adjust the pH value to 9-10; and prepare a suspension. S2. Mix tetraethyl orthosilicate with an appropriate amount of ethanol solution to prepare a mixed solution; S3. While continuously stirring, heat the suspension to 25-35°C, slowly add the mixed solution dropwise into it, and continue stirring the reaction for 8-12 hours after the addition is complete. S4. Collect solid particles, wash them sequentially with ethanol and deionized water, and then vacuum dry them.

3. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 2, characterized in that, The method for preparing the pretreated iron oxide powder in step S1 includes the following steps: S11. Acid washing treatment of iron oxide powder; S12. Disperse the acid-washed powder in anhydrous ethanol solution to form a ferric oxide / ethanol suspension; place γ-aminopropyltriethoxysilane in another part of anhydrous ethanol solution, adjust the solution to acidity, add deionized water, and then sonicate to form a hydrolysate. S13. Keep the iron oxide / ethanol suspension stirred, and slowly add the hydrolysate dropwise under nitrogen protection. Reflux at 60-80°C for 4-6 hours. After cooling to room temperature, magnetically separate the solid product, wash with anhydrous ethanol, and vacuum dry.

4. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 3, characterized in that, The acid washing treatment of the iron oxide powder in step S11 includes: Ferric oxide powder is immersed in dilute nitric acid or dilute hydrochloric acid solution, and a solid is obtained by magnetic separation. The solid is then washed alternately with deionized water and ethanol until the washing solution is neutral.

5. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 1, characterized in that, The preparation method of the modified polyimide nanofibers includes the following steps: S1. Immerse polyimide nanofibers in potassium hydroxide solution and stir at 60-80°C for 0.5-2 hours; cool to room temperature, wash with deionized water until neutral, and vacuum dry; S2. Place it in anhydrous ethanol solution, stir thoroughly, adjust the pH to 4-5, heat to 70-80℃, add γ-aminopropyltriethoxysilane solution, and reflux for 6-10 hours. S3. Wash repeatedly with anhydrous ethanol solution until the washing solution is neutral, then vacuum dry.

6. The solvent-free insulating elastic coating for preventing stray currents in railway tracks according to claim 1, characterized in that, The functional fillers include titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder.

7. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 6, characterized in that, The mass ratio of titanium dioxide powder, hollow microspheres, mica powder, and aluminum oxide powder is 3:1:5:

1.

8. The solvent-free insulating elastic coating for preventing stray current in railway tracks according to claim 1, characterized in that, The thickener is BYK430; the wetting and dispersing agent is BYK220S; the defoamer is BYK1790; and the leveling agent is EFKA3600.

9. The solvent-free insulating elastic coating for preventing stray currents in railway tracks according to claim 1, characterized in that, The mass ratio of component A to component B is 100:(20-30).

10. The method for preparing a solvent-free insulating elastic coating for track use to prevent stray current according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Add polyaspartic acid ester resin, aminoalkoxysilane and wetting and dispersing agent to a dispersion tank, heat to 30-40℃, and stir and disperse at 600-900 rpm for 3-5 min; slowly add modified polyimide nanofibers, and after the addition is complete, stir and disperse at 1000-1500 rpm for 30-40 min; then ultrasonically stir and disperse under ice-water bath conditions for 15-30 min; S2. Heat to room temperature, reduce the rotation speed by 600-900 rpm, slowly add Fe3O4@SiO2, and after the addition is complete, stir and disperse at 1000-1500 rpm for 15-30 min; then, under ice-water bath conditions, ultrasonically stir and disperse for 10-15 min. S3. Heat to room temperature, reduce the rotation speed by 300-500 rpm, slowly add the functional filler, and after the addition is complete, stir and disperse at 1000-1500 rpm for 10-15 minutes; then reduce the rotation speed to 300-500 rpm, add the thickener and leveling agent in sequence, and stir at 1000-1500 rpm for 10-15 minutes. S4. Transfer the material into a sand mill for grinding. After grinding to a fineness of <40μm, add defoamer and stir for 10-15 minutes at 1000-1500 rpm. Filter and dispense to obtain ingredient A. S5. Add the aliphatic isocyanate trimer to a dispersion tank, stir and disperse at 600-900 rpm for 5-8 min, filter and dispense to obtain ingredient B; S6. Mix ingredients A and B together and stir well.

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