Low-temperature-resistant anti-icing film coating for railway steel rail and turnout and preparation method of low-temperature-resistant anti-icing film coating

Abstract

The invention belongs to the technical field of functional coatings for rail transit, and discloses a low-temperature-resistant anti-icing film coating for a railway steel rail and a turnout and a preparation method of the low-temperature-resistant anti-icing film coating. The coating composition comprises epoxidized soybean oil ester modified lithium-based grease, fluorosilane modified nano silicon dioxide and boron nitride composite filler, a silane-titanate composite customized coupling agent, a latent curing agent, an antioxidant and an ultraviolet light absorber. Through the synergistic effect of the low-surface-energy filler and the cold-resistant matrix, the anti-icing performance and mechanical stability of the coating under the low-temperature condition and the bonding performance of the coating and a metal base material are improved. The invention also provides a preparation method of the laminated coating, the preparation method comprises the steps of preparation of the coating composition, surface pretreatment of the steel rail or the turnout, electrostatic spraying and low-temperature curing, the technological process is controllable, the applicability is high, and the method is suitable for engineering application of complex structure surfaces of the railway steel rail and the turnout.

Description

Technical Field

[0001] This invention belongs to the field of functional coating technology for rail transit, specifically relating to a low-temperature resistant and anti-icing coating for railway rails and turnouts and its preparation method. Background Technology

[0002] In cold and frigid regions, railways are exposed to complex environments such as low temperatures, high humidity, wind, snow, and frequent freeze-thaw cycles during winter. The surfaces of rails and turnouts are highly susceptible to icing, snow accumulation, and frost, especially in structurally complex and stress-concentrated areas such as turnout switch rails, slides, and frogs. The formation of ice not only reduces wheel-rail adhesion and increases braking distance, but can also cause turnout malfunctions, jamming, or even failure, potentially leading to traffic accidents and posing a significant threat to railway transportation safety.

[0003] Currently, anti-icing measures for railway rails and turnouts mainly include manual or mechanical de-icing, chemical de-icing agents, and surface protective coatings. Manual and mechanical de-icing are inefficient, labor-intensive, and unsuitable for high-density railway lines; chemical de-icing agents require frequent application, resulting in high operation and maintenance costs. In contrast, anti-icing coatings, as a passive protection method, offer advantages such as flexible construction, long-lasting action, and minimal operational disruption, and are gradually gaining attention. However, existing anti-icing coatings are mostly general-purpose superhydrophobic or low surface energy coatings, primarily used in construction, aviation, or wind power, and are insufficient to meet the comprehensive requirements of railway rails and turnouts under heavy loads, high-frequency friction, and extreme low-temperature conditions. On the one hand, some superhydrophobic coatings rely on micro-nano structures to achieve anti-icing effects, making them susceptible to damage under external impacts or wheel-rail friction, resulting in insufficient wear resistance; on the other hand, many coatings are prone to embrittlement at low temperatures, leading to decreased adhesion or even peeling, making long-term service unsustainable. Furthermore, existing coating systems have limited adaptability to the complex structures of turnouts, and the coating thickness and performance uniformity are difficult to guarantee. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a low-temperature resistant anti-icing coating for railway rails and turnouts and its preparation method. By constructing a coating system with epoxidized soybean oil ester modified lithium-based grease as the matrix, fluorosilane modified nano-silica and boron nitride composite filler synergistically enhanced, the coating achieves a synergistic improvement in anti-icing properties, adhesion and durability in low-temperature environments. Through electrostatic spraying and low-temperature curing processes, it is suitable for engineering applications on the complex structural surfaces of railway rails and turnouts.

[0005] The objective of this invention can be achieved through the following technical solutions: A low-temperature resistant and anti-icing coating for railway rails and turnouts, wherein the coating is formed by curing a coating composition, the coating composition comprising the following raw materials in parts by weight: 40-60 parts of epoxidized soybean oil modified lithium-based grease, 15-25 parts of fluorosilane modified nano-silica and boron nitride composite filler, 2-5 parts of silane-titanium ester composite coupling agent, 3-6 parts of latent curing agent, 0.5-1.5 parts of antioxidant, and 0.3-0.8 parts of ultraviolet absorber.

[0006] More preferably, in the fluorosilane-modified nano-silica and boron nitride composite filler, the mass ratio of fluorosilane-modified nano-silica to boron nitride is 1:(0.5-2).

[0007] More preferably, the epoxidized soybean oil ester modified lithium-based ester is prepared by the following method: the lithium-based ester is heated to 90-100°C to melt it, epoxidized soybean oil ester and stannous octoate catalyst are added, and the mixture is stirred at a constant temperature of 90-100°C for 30-60 min, and then cooled to 40-50°C to obtain the epoxidized soybean oil ester modified lithium-based ester; wherein, the amount of epoxidized soybean oil ester added is 20-40% of the lithium-based ester mass, and the amount of stannous octoate catalyst added is 0.1-0.3% of the total mass of the lithium-based ester and epoxidized soybean oil ester.

[0008] More preferably, the fluorosilane-modified nano-silica in the fluorosilane-modified nano-silica and boron nitride composite filler is prepared by the following method: nano-silica with a particle size of 20-50 nm is dispersed in anhydrous ethanol, perfluorooctyltriethoxysilane is added, the pH of the system is adjusted to 4-5 with acetic acid, and the reaction is stirred at 60-70°C for 2-3 h. After centrifugation and vacuum drying at 60°C for 4 h, the nano-silica is obtained. The amount of perfluorooctyltriethoxysilane added is 5-10% of the mass of the nano-silica.

[0009] More preferably, the silane-titanium ester composite coupling agent is prepared by the following method: γ-glycidoxypropyltrimethoxysilane and isopropyl triisostearate titanate are mixed at a mass ratio of 2:1, anhydrous ethanol is added, and the mixture is stirred at 40-50°C for 15-20 min, then cooled to room temperature to obtain the final product; wherein, the amount of anhydrous ethanol added is 5-8% of the mass of the mixture of γ-glycidoxypropyltrimethoxysilane and isopropyl triisostearate titanate.

[0010] More preferably, the latent curing agent is an imidazole latent curing agent, selected from one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 1-benzyl-2-methylimidazole, and its activation temperature is 70-80°C.

[0011] A method for preparing a low-temperature resistant and anti-icing coating for railway rails and turnouts includes the following steps: S1. Epoxy soybean oil ester modified lithium ester is heated and a latent curing agent is added and stirred until uniform. Then, fluorosilane modified nano silica and boron nitride composite filler, antioxidant and ultraviolet absorber are added. After dispersion treatment, a silane-titanium ester composite coupling agent is added to obtain the coating composition. S2. Perform surface pretreatment on the rails or turnouts, including sandblasting to remove rust, degreasing with anhydrous ethanol, and air drying. S3. The coating composition is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device; S4. The coated substrate is cured to obtain a low-temperature resistant and anti-icing coating.

[0012] More preferably, the dispersion treatment in step S1 includes high-speed shear dispersion and ultrasonic dispersion, wherein the high-speed shear dispersion has a rotation speed of 3000-5000 r / min and a time of 15-20 min, the ultrasonic dispersion has a power of 200-500 W, a frequency of 20-40 kHz, and a time of 30-40 min, and the system temperature is controlled not to exceed 50°C during the dispersion process; the stirring temperature after the coupling agent is added is 40-50°C, the time is 20-30 min, and the standing degassing time is 10-15 min.

[0013] More preferably, the coating film formation in step S3 is carried out by electrostatic spraying, with a spraying voltage of 30-60 kV, a gun distance of 20-30 cm, a spraying speed of 0.5-1 m / s, and a dry film thickness of 50-80 μm; the curing treatment in step S4 is carried out at 60-80℃ for 1-2 h.

[0014] The beneficial effects of this invention are: This invention utilizes epoxidized soybean oil ester-modified lithium-based grease as a cold-resistant matrix. Compared to traditional rigid resin systems, it maintains good flexibility and continuity under low-temperature conditions, effectively reducing the risk of coating brittleness and peeling under extreme low temperatures and freeze-thaw cycles. Simultaneously, the introduced fluorosilane-modified nano-silica and boron nitride composite filler form a synergistic reinforcing effect in the coating. On one hand, by reducing the surface energy of the coating and inhibiting ice crystal nucleation, it reduces the bonding strength between the ice layer and the coating interface, thus achieving a stable and durable anti-icing effect. On the other hand, the layered structure and mechanical stability of boron nitride improve the wear resistance of the coating under wheel-rail friction and the external forces of ice and snow, preventing the anti-icing function from rapidly diminishing due to surface structure damage. The introduction of a silane-titanium ester composite coupling agent forms a stable interface transition layer between the coating and the rail and turnout metal substrate, significantly enhancing the coating's adhesion and interface durability under low-temperature conditions, reducing the possibility of coating peeling and flaking during long-term service. In addition, the use of imidazole latent curing agents combined with medium and low temperature curing processes allows the coating to complete cross-linking and curing at lower curing temperatures, which helps maintain the original mechanical properties and stress state of the rails and turnouts, and adapts to the needs of on-site construction and maintenance. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 This is a comparison chart of the ice adhesion strength of the coating samples in the examples and comparative examples. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: Verification of the feasibility and process stability of the coating of the present invention under the minimum addition amount and mild process conditions.

[0019] I. Preparation of Epoxidized Soybean Oil Ester Modified Lithium-Based Lithium ... 769.23 g of lithium-based grease was added to a reactor and heated to 90°C under nitrogen protection. The mixture was stirred at 200 r / min to completely melt the lithium-based grease and form a homogeneous mobile phase. Subsequently, 230.77 g of epoxidized soybean oil ester was added in batches at 3-min intervals. The mixture was stirred continuously while maintaining the system temperature at 90°C to ensure thorough mixing of the epoxidized soybean oil ester and the lithium-based grease. After homogeneous mixing, 2.00 g of stannous octoate catalyst was added to the system, and the mixture was stirred at a constant temperature of 90°C for 30 min. After the reaction was completed, heating was stopped, stirring was continued, and the mixture was allowed to cool naturally to 40°C to obtain epoxidized soybean oil ester modified lithium-based grease.

[0020] II. Preparation of Fluorosilane-Modified Nano-Silica 100.0 g of 25 nm nano-silica was weighed and added to 1000 mL of anhydrous ethanol. After pre-stirring at 600 r / min for 10 min at room temperature, ultrasonic dispersion was performed at 300 W, 20 kHz, and 30 min, with the system temperature controlled to not exceed 30 °C during dispersion, to obtain a uniform nano-silica ethanol dispersion. Then, 8.0 g of perfluorooctyltriethoxysilane was added to the dispersion at 400 r / min, followed by the addition of glacial acetic acid to adjust the pH of the system to 4. The temperature was raised to 60 °C and stirred at this temperature for 2 h. After the reaction, the system was cooled to room temperature, transferred to a centrifuge tube, centrifuged at 8000 r / min for 10 min, the supernatant was discarded, and the precipitate was washed twice with anhydrous ethanol. The precipitate was then dried in a vacuum drying oven at 60 °C for 4 h, ground, and sieved to obtain fluorosilane-modified nano-silica.

[0021] III. Preparation of Silane-Titanium Ester Composite Custom Coupling Agents Weigh 20.0 g of γ-glycidoxypropyltrimethoxysilane and 10.0 g of isopropyl triisostearate titanate into a dry three-necked flask and mix at 300 r / min for 5 min under nitrogen protection. Then add 1.8 g of anhydrous ethanol and continue stirring to make the system homogeneous. Heat the system to 40 °C and stir at this temperature for 15 min to allow the silane and titanate to fully mix in the ethanol medium to form a homogeneous liquid system. After the reaction is completed, stop heating, continue stirring and cool naturally to room temperature to obtain the silane-titanate composite coupling agent.

[0022] IV. Preparation of Low-Temperature Resistant and Anti-icing Coating for Railway Rails and Turnouts The low-temperature resistant and anti-icing coating for railway rails and turnouts is formed by curing a coating composition. The coating composition contains the following raw materials in parts by weight: 40 parts of epoxidized soybean oil modified lithium ester, 15 parts of fluorosilane modified nano silica and boron nitride composite filler, 2 parts of silane-titanium ester composite coupling agent, 3 parts of latent curing agent, 0.5 parts of antioxidant, and 0.3 parts of ultraviolet absorber.

[0023] The preparation method of the low-temperature resistant and anti-icing coating for railway rails and turnouts is as follows: S1. Add 400 g of epoxidized soybean oil ester modified lithium-based ester to a mixing vessel and heat to 40°C. Add 30 g of latent curing agent under mechanical stirring and continue stirring for 10 min to obtain the base solution. Subsequently, add 150 g of fluorosilane-modified nano-silica and boron nitride composite filler (fluorosilane-modified nano-silica: boron nitride mass ratio of 1:0.5), 5 g of antioxidant 1010, and 3 g of ultraviolet absorber UV-328 to the base solution in sequence. Perform high-speed shear dispersion at room temperature, with a shearing speed of 3000 r / min and a shearing time of 15 min. After high-speed shearing, perform ultrasonic dispersion treatment on the system with an ultrasonic power of 200 W, a frequency of 20 kHz, and an ultrasonic time of 30 min. The system temperature does not exceed 50°C during the dispersion process. After dispersion, 20 g of silane-titanium ester composite custom coupling agent was added, the system was raised to 40°C, and stirred at a constant temperature of 200 r / min for 20 min. Then it was cooled to room temperature and allowed to stand for degassing for 10 min to obtain a uniform and stable coating composition.

[0024] S2. Select railway rail or turnout steel samples, first perform sandblasting to remove rust, so that the surface roughness of the substrate Ra≈30 μm; then degrease and clean with anhydrous ethanol to remove oil and impurities, and finally air dry at room temperature for later use.

[0025] S3. The coating composition obtained in step S1 is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device. The spraying voltage is 30 kV, the distance between the spray gun and the substrate surface is 30 cm, the spraying speed is 0.5 m / s, and the dry film thickness is controlled to be 50 μm by multiple reciprocating sprays.

[0026] S4. Place the coated substrate in a hot air circulating oven and cure it at 60°C for 1 hour. Then remove it and let it cool naturally at room temperature to obtain a low-temperature resistant and anti-icing coating for railway rails and turnouts.

[0027] Example 2: Verification shows that by increasing the amount of each component added to the coating composition and coordinating with appropriate dispersion, coating and curing conditions, a low-temperature anti-icing coating with a continuous structure and complete film formation can still be stably prepared.

[0028] The preparation steps of the epoxidized soybean oil ester modified lithium-based ester, fluorosilane modified nano-silica, and silane-titanium ester composite custom coupling agent are the same as those in Example 1.

[0029] The low-temperature resistant and anti-icing coating for railway rails and turnouts is formed by curing a coating composition. The coating composition contains the following raw materials in parts by weight: 60 parts of epoxidized soybean oil modified lithium ester, 25 parts of fluorosilane modified nano silica and boron nitride composite filler, 5 parts of silane-titanium ester composite coupling agent, 6 parts of latent curing agent, 1.5 parts of antioxidant, and 0.8 parts of ultraviolet absorber.

[0030] The preparation method of the low-temperature resistant and anti-icing coating for railway rails and turnouts is as follows: S1. Add 600 g of epoxidized soybean oil ester modified lithium-based grease to a mixing vessel equipped with mechanical stirring and temperature control, heat to 50℃, add 60 g of latent curing agent under stirring at 300 r / min, and continue stirring for 15 min until homogeneous to obtain the base liquid; then add 83.33 g of fluorosilane modified nano-silica and 166.67 g of boron nitride (fluorosilane modified nano-silica and boron nitride composite filler), 15 g of antioxidant 1010 and 8 g of ultraviolet absorber UV-328 in sequence, and perform high-speed shear dispersion at room temperature, with a shear speed of 5000 r / min and a time of 20 min; after completion, perform ultrasonic dispersion, with an ultrasonic power of 500 W, a frequency of 40 kHz and a time of 40 min, and use an ice-water bath to control the temperature so that the system temperature does not exceed 50℃ during the dispersion process; after dispersion, add 50 g of silane-titanium ester composite coupling agent, raise the system temperature to 50℃, and stir at a constant temperature of 300 r / min for 30 minutes. After 1 minute, the mixture was cooled to room temperature and allowed to stand for 15 minutes to degas, resulting in a uniform and stable coating composition.

[0031] S2. Select railway rail or turnout steel samples and perform sandblasting, anhydrous ethanol degreasing, and natural air drying on their surfaces in sequence. After sandblasting, the surface roughness of the substrate is controlled to Ra≈50 μm, and it is ensured that the pretreated surface is free of oil, oxide scale, and impurities.

[0032] S3. The coating composition obtained in step S1 is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device. The spraying voltage is 60 kV, the distance between the spray gun and the substrate surface is 20 cm, the spraying speed is 1.0 m / s, and the dry film thickness is controlled to be 80 μm by multiple reciprocating sprays.

[0033] S4. Place the coated substrate in a hot air circulating oven and cure it at 80°C for 2 hours. Then remove it and let it cool naturally at room temperature to obtain a low-temperature resistant and anti-icing coating for railway rails and turnouts.

[0034] Example 3: This example illustrates that, within the range of raw material ratios and process conditions described in the technical solution of this invention, by selecting typical values ​​for each component and preparation parameters, a low-temperature resistant and anti-icing coating with uniform structure and continuous film formation can be stably prepared.

[0035] The preparation steps of the epoxidized soybean oil ester modified lithium-based ester, fluorosilane modified nano-silica, and silane-titanium ester composite custom coupling agent are the same as those in Example 1.

[0036] The low-temperature resistant and anti-icing coating for railway rails and turnouts is formed by curing a coating composition. The coating composition contains the following raw materials in parts by weight: 50 parts of epoxidized soybean oil modified lithium ester, 20 parts of fluorosilane modified nano silica and boron nitride composite filler, 3.5 parts of silane-titanium ester composite coupling agent, 4.5 parts of latent curing agent, 1.0 part of antioxidant, and 0.55 parts of ultraviolet absorber.

[0037] The preparation method of the low-temperature resistant and anti-icing coating for railway rails and turnouts is as follows: S1. Add 500 g of epoxidized soybean oil ester modified lithium-based grease to a mixing vessel equipped with a mechanical stirrer and temperature control device, heat to 45℃, add 45 g of latent curing agent under stirring at 250 r / min, and continue stirring for 12 min until completely dissolved to obtain the base liquid; then add 88.89 g of fluorosilane modified nano silica and 111.11 g of boron nitride to form a fluorosilane modified nano silica and boron nitride composite filler, 10 g of antioxidant 1010 and 5.5 g of ultraviolet absorber UV-328 in sequence, and perform high-speed shear dispersion at room temperature, with a shear speed of 4000 r / min and a time of 18 min; after completion, the system is ultrasonically dispersed with an ultrasonic power of 350 W, a frequency of 30 kHz and a time of 35 min, and the temperature is controlled by an ice-water bath to ensure that the system temperature does not exceed 50℃ during the dispersion process. After dispersion, 35 g of silane-titanium ester composite custom coupling agent was added to the system. The system temperature was maintained at 45℃ and stirred at a constant speed of 250 r / min for 25 min. Then, the system was cooled to room temperature and allowed to stand for degassing for 12 min to obtain a uniform and stable coating composition.

[0038] S2. Select railway rail or turnout steel samples, and perform sandblasting, anhydrous ethanol degreasing, and natural air drying on their surfaces in sequence to make the surface roughness of the substrate Ra≈40 μm after sandblasting, and ensure that the surface is free of oil, oxide scale and impurities.

[0039] S3. The coating composition obtained in step S1 is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device. The spraying voltage is 45 kV, the distance between the spray gun and the substrate surface is 25 cm, the spraying speed is 0.75 m / s, and the dry film thickness is controlled to be 65 μm by multiple reciprocating sprays.

[0040] S4. Place the coated substrate in a hot air circulating oven and cure it at 70°C for 1.5 h. Then remove it and allow it to cool naturally at room temperature to obtain a low-temperature resistant and anti-icing coating for railway rails and turnouts.

[0041] Comparative Example 1: In this comparative example, fluorosilane-modified nano-silica was replaced with unmodified nano-silica.

[0042] The preparation steps of the epoxidized soybean oil ester modified lithium-based ester and the silane-titanium ester composite custom coupling agent are the same as those in Example 1.

[0043] The low-temperature resistant and anti-icing coating for railway rails and turnouts is formed by curing a coating composition. The coating composition contains the following raw materials in parts by weight: 50 parts of epoxidized soybean oil modified lithium ester, 20 parts of unmodified nano-silica and boron nitride composite filler, 3.5 parts of silane-titanium ester composite coupling agent, 4.5 parts of latent curing agent, 1.0 part of antioxidant, and 0.55 parts of ultraviolet absorber.

[0044] The preparation method of the low-temperature resistant and anti-icing coating for railway rails and turnouts is as follows: S1. Add 500 g of epoxidized soybean oil ester modified lithium-based ester to a mixing vessel equipped with a mechanical stirrer and temperature control device, heat to 45℃, add 45 g of latent curing agent (1-benzyl-2-methylimidazolium) under stirring at 250 r / min, and continue stirring for 12 min until completely dissolved to obtain the base liquid; then add 88.89 g of unmodified nano silica and 111.11 g of boron nitride composite filler composed of unmodified nano silica and boron nitride, 10 g of antioxidant and 5.5 g of ultraviolet absorber in sequence, and perform high-speed shear dispersion at room temperature, with a shear speed of 4000 r / min and a time of 18 min; after completion, the system is ultrasonically dispersed with an ultrasonic power of 350 W, a frequency of 30 kHz and a time of 35 min, and the temperature is controlled by an ice-water bath to ensure that the system temperature does not exceed 50℃ during the dispersion process. After dispersion, 35 g of silane-titanium ester composite custom coupling agent was added to the system. The system temperature was maintained at 45℃ and stirred at a constant speed of 250 r / min for 25 min. Then, the system was cooled to room temperature and allowed to stand for degassing for 12 min to obtain the coating composition.

[0045] S2. Select railway rail or turnout steel samples, and perform sandblasting, anhydrous ethanol degreasing, and natural air drying on their surfaces in sequence to make the surface roughness of the substrate Ra≈40 μm after sandblasting, and ensure that the surface is free of oil, oxide scale and impurities.

[0046] S3. The coating composition obtained in step S1 is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device. The spraying voltage is 45 kV, the distance between the spray gun and the substrate surface is 25 cm, the spraying speed is 0.75 m / s, and the dry film thickness is controlled to be 65 μm by multiple reciprocating sprays.

[0047] S4. Place the coated substrate in a hot air circulating oven and cure it at 70°C for 1.5 h. Then remove it and let it cool naturally at room temperature to obtain the coating of Comparative Example 1.

[0048] Comparative Example 2: Custom coupling agent without silane-titanium ester composite.

[0049] The preparation steps of the epoxidized soybean oil ester modified lithium-based ester and the fluorosilane modified nano-silica are the same as those in Example 1.

[0050] The low-temperature resistant and anti-icing coating for railway rails and turnouts is formed by curing a coating composition. The coating composition contains the following raw materials in parts by weight: 50 parts of epoxidized soybean oil modified lithium ester, 20 parts of fluorosilane modified nano silica and boron nitride composite filler, 4.5 parts of latent curing agent, 1.0 part of antioxidant, and 0.55 parts of ultraviolet absorber.

[0051] The preparation method of the low-temperature resistant and anti-icing coating for railway rails and turnouts is as follows: S1. Add 500 g of epoxidized soybean oil ester modified lithium-based ester to a mixing vessel and heat to 45°C. Add 45 g of latent curing agent (1-benzyl-2-methylimidazolium) while stirring at 250 r / min, and continue stirring for 12 min until completely dissolved to obtain the base liquid. Then, add 88.89 g of fluorosilane-modified nano-silica and 111.11 g of boron nitride (a composite filler consisting of fluorosilane-modified nano-silica and boron nitride), 10 g of antioxidant, and 5.5 g of UV absorber sequentially. Perform high-speed shear dispersion at room temperature (4000 r / min, 18 min). After dispersion, perform ultrasonic dispersion at 350 W, 30 kHz, and 35 min, using an ice-water bath to control the temperature and ensure the system temperature does not exceed 50°C during dispersion. After dispersion, cool the system to room temperature and allow it to stand for 12 min to degas, obtaining the coating composition.

[0052] S2. Select railway rail or turnout steel samples and perform sandblasting, anhydrous ethanol degreasing, and natural air drying on their surfaces in sequence to make the surface roughness of the substrate Ra≈40 μm after sandblasting, and ensure that the surface is free of oil, oxide scale and impurities.

[0053] S3. The coating composition obtained in step S1 is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device. The spraying voltage is 45 kV, the distance between the spray gun and the substrate surface is 25 cm, and the spraying speed is 0.75 m / s. The dry film thickness is controlled to be 65 μm by multiple reciprocating sprays.

[0054] S4. Place the coated substrate in a hot air circulating oven and cure it at 70°C for 1.5 h. Then remove it and let it cool naturally at room temperature to obtain the film coating of Comparative Example 2.

[0055] Performance testing 1. Ice adhesion strength test The prepared coated sample was placed in a constant temperature environment, and an ice layer of specified area and thickness was prepared on the coating surface using a mold. The sample was then transferred to a low-temperature test chamber and maintained at −10℃ to −20℃ for a certain period. Using a shear method, gradually increasing external forces were applied to the ice layer, and the maximum force at which the ice layer detached completely was recorded. The ice adhesion strength was calculated based on the area of ​​the ice layer subjected to force, expressed in kPa. Each group of samples was tested at least three times, and the average value was taken as the test result.

[0056] 2. Low-temperature bending performance test Place the coated sample in a -50℃ low-temperature environment for at least 2 hours; then, while maintaining the low temperature, conduct a bending test on the sample with a specified bending radius; after the test, visually or microscopically inspect the coating surface for cracks, peeling or other damage, and record the test results.

[0057] 3. Adhesion test According to the cross-cut test method of GB / T 9286, a grid with a specified spacing is drawn on the coating surface using a cross-cutting tool; then, standard tape is attached to the grid area and quickly peeled off; observe the peeling of the coating in the grid area, and determine the adhesion level according to the standard.

[0058] The performance test results are shown in Table 1 below.

[0059] Table 1. Performance test results of the coating in the examples and comparative examples

[0060] As shown in Table 1, the coatings prepared in Examples 1-3 exhibited excellent and stable comprehensive performance in terms of ice adhesion strength, low-temperature bending performance, and adhesion. The ice adhesion strength of the coatings in the examples was controlled at a low level, significantly lower than that of Comparative Examples 1 and 2. This indicates that by introducing fluorosilane-modified nano-silica into the coating system, a low surface energy structure can be constructed on the coating surface, effectively weakening the interfacial bonding force between the ice layer and the coating, thereby reducing the external force required for ice desorption. Meanwhile, no cracks appeared in the examples at −50℃, indicating that the epoxidized soybean oil ester-modified lithium-based ester matrix maintains good flexibility and deformation adaptability in extremely low-temperature environments, effectively alleviating the low-temperature stress concentration phenomenon. Furthermore, Comparative Example 2, due to the lack of a silane-titanium ester composite coupling agent, had insufficient interfacial bonding between the coating and the metal substrate and filler, making it prone to interfacial mismatch during low-temperature bending, resulting in slight cracking of the coating accompanied by a significant decrease in adhesion. In addition, the composite filler system formed by boron nitride and modified nano-silica played a synergistic reinforcing role in the examples, which not only improved the structural stability of the coating, but also prevented the coating from becoming embrittled in low-temperature environments while maintaining low ice adhesion strength.

[0061] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A low-temperature resistant and anti-icing coating for railway rails and turnouts, characterized in that, The coating is formed by curing a coating composition, which contains the following raw materials in parts by weight: 40-60 parts of epoxidized soybean oil modified lithium ester, 15-25 parts of fluorosilane modified nano silica and boron nitride composite filler, 2-5 parts of silane-titanium ester composite coupling agent, 3-6 parts of latent curing agent, 0.5-1.5 parts of antioxidant, and 0.3-0.8 parts of ultraviolet absorber.

2. The low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 1, characterized in that, In the fluorosilane-modified nano-silica and boron nitride composite filler, the mass ratio of fluorosilane-modified nano-silica to boron nitride is 1:(0.5-2).

3. The low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 1, characterized in that, The epoxidized soybean oil ester modified lithium-based ester is prepared by the following method: the lithium-based ester is heated to 90-100°C to melt it, epoxidized soybean oil ester and stannous octoate catalyst are added, and the mixture is stirred at a constant temperature of 90-100°C for 30-60 min, and then cooled to 40-50°C to obtain the epoxidized soybean oil ester modified lithium-based ester; wherein, the amount of epoxidized soybean oil ester added is 20-40% of the lithium-based ester mass, and the amount of stannous octoate catalyst added is 0.1-0.3% of the total mass of the lithium-based ester and epoxidized soybean oil ester.

4. The low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 1, characterized in that, The fluorosilane-modified nano-silica in the fluorosilane-modified nano-silica and boron nitride composite filler is prepared by the following method: nano-silica with a particle size of 20-50 nm is dispersed in anhydrous ethanol, perfluorooctyltriethoxysilane is added, the pH of the system is adjusted to 4-5 with acetic acid, and the reaction is stirred at 60-70℃ for 2-3 h. After centrifugation and vacuum drying at 60℃ for 4 h, the nano-silica is obtained. The amount of perfluorooctyltriethoxysilane added is 5-10% of the mass of the nano-silica.

5. The low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 1, characterized in that, The silane-titanium ester composite coupling agent is prepared by the following method: γ-glycidoxypropyltrimethoxysilane and isopropyl triisostearate titanate are mixed at a mass ratio of 2:1, anhydrous ethanol is added, and the mixture is stirred at 40-50°C for 15-20 min, then cooled to room temperature to obtain the final product; wherein, the amount of anhydrous ethanol added is 5-8% of the mass of the mixture of γ-glycidoxypropyltrimethoxysilane and isopropyl triisostearate titanate.

6. The low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 1, characterized in that, The latent curing agent is an imidazole latent curing agent, selected from one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 1-benzyl-2-methylimidazole, and its activation temperature is 70-80℃.

7. A method for preparing a low-temperature resistant and anti-icing coating for railway rails and turnouts as described in claim 1, characterized in that, Includes the following steps: S1. Epoxy soybean oil ester modified lithium ester is heated and a latent curing agent is added and stirred until uniform. Then, fluorosilane modified nano silica and boron nitride composite filler, antioxidant and ultraviolet absorber are added. After dispersion treatment, a silane-titanium ester composite coupling agent is added to obtain the coating composition. S2. Perform surface pretreatment on the rails or turnouts, including sandblasting to remove rust, degreasing with anhydrous ethanol, and air drying. S3. The coating composition is sprayed onto the pretreated substrate surface using a high-voltage electrostatic spraying device; S4. The coated substrate is cured to obtain a low-temperature resistant and anti-icing coating.

8. The method for preparing a low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 7, characterized in that, The dispersion treatment in step S1 includes high-speed shear dispersion and ultrasonic dispersion. The high-speed shear dispersion is performed at a rotation speed of 3000–5000 r / min for 15–20 min. The ultrasonic dispersion is performed at a power of 200–500 W, a frequency of 20–40 kHz, and a time of 30–40 min. The system temperature is controlled to not exceed 50°C during the dispersion process. The stirring temperature after the coupling agent is added is 40–50°C for 20–30 min, and the standing degassing time is 10–15 min.

9. The method for preparing a low-temperature resistant and anti-icing coating for railway rails and turnouts according to claim 7, characterized in that, In step S3, the coating film is formed by electrostatic spraying with a spraying voltage of 30–60 kV, a gun distance of 20–30 cm, a spraying speed of 0.5–1 m / s, and a dry film thickness of 50–80 μm. In step S4, the curing treatment is carried out at 60–80℃ for 1–2 h.

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