A weather-resistant railway turnout coating and a method for preparing the same

Abstract

The application discloses a weather-resistant railway turnout coating and a preparation method thereof, and relates to the technical field of railway turnout coatings. Fluorosilane modified graphene oxide nanosheets rich in fluorinated alkyl groups and active silicon hydroxyl groups are obtained; a weather-resistant polyurethane prepolymer with a main chain block containing fluorine and isocyanate end groups is synthesized; a nanocomposite prepolymer homogeneous phase is obtained; a high-activity weather-resistant coating stock solution with a self-leveling property is prepared; a interpenetrating network structure of fluorosilicon modified nanophase and high molecular organic phase is formed in the coating system, and the weather-resistant railway turnout coating is formed in situ on the surface of a metal base. The application significantly improves the rheological stability and extremely high thixotropy of the nanocomposite system.

Description

Technical Field

[0001] This invention relates to the field of railway turnout coating technology, and in particular to a weather-resistant railway turnout coating and its preparation method. Background Technology

[0002] With the rapid development of high-speed railways and heavy-haul transportation networks, railway turnouts, as core hub nodes of the track system, are exposed to the outdoors for extended periods and subjected to intense high-frequency friction and mechanical impact from train wheels. Therefore, applying protective coatings to the surface of turnout metal substrates has become a standard process for extending their service life and reducing maintenance frequency. However, in actual service environments with extreme weather alternation and high-frequency vibration coupling, the application of existing turnout protective coatings faces many challenges.

[0003] Traditional turnout coating preparation methods typically rely on conventional epoxy resin or ordinary polyurethane systems and physically blended fillers. This leads to severe molecular chain degradation, coating chalking, and significant replacement costs under outdoor conditions involving prolonged exposure to strong ultraviolet radiation and extreme temperature variations. Furthermore, with increasing train axle load and traffic density, the synergistic requirements for the coating's comprehensive mechanical properties and weather resistance have risen sharply. Introducing antioxidants or nano-reinforcing materials using traditional physical additive methods easily triggers secondary agglomeration of nanoparticles and the precipitation and loss of additives after long-term use, making it increasingly difficult to ensure the stability of the coating's internal microstructure and the consistency of its macroscopic properties.

[0004] Traditional coating film formation and curing mechanisms are usually designed for conventional protective environments with relatively static or single stress. They cannot take into account the differentiated distribution of the coating surface's hydrophobic self-cleaning requirements and the underlying layer's strong chemical anchoring requirements. They cannot effectively resist the dual damage of climate and mechanical stress by constructing an impact-resistant micro-interpenetrating network structure, ultimately leading to premature peeling and failure of the coating under complex working conditions. Summary of the Invention

[0005] One objective of this invention is to provide a weather-resistant railway turnout coating and its preparation method. This invention significantly improves the rheological stability and extremely high thixotropy of the nanocomposite system.

[0006] A method for preparing a weather-resistant railway turnout coating according to an embodiment of the present invention, the method comprising: A dispersion of graphene oxide was subjected to ultrasonic cavitation and covalent grafting reaction with a fluorinated polyether silane coupling agent in an acidic alcohol-water medium to obtain fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups. Under the protection of an inert gas and in the presence of a catalyst, aliphatic diisocyanate, polytetrafluoroethylene glycol and polycarbonate glycol were subjected to a stepwise heating polymerization reaction to synthesize a weather-resistant polyurethane prepolymer with fluorinated main chain blocks and isocyanate end groups. Fluorosilane-modified graphene oxide nanosheets were added to the weather-resistant polyurethane prepolymer at a predetermined mass fraction, and multi-stage gradient temperature-controlled mixing was carried out using a vacuum high-shear emulsifier to form an isotropic three-dimensional network dispersion structure of the nanosheets in the prepolymer matrix, thereby obtaining a homogeneous phase of nanocomposite prepolymer. A hindered amine light stabilizer presolvent and an amino-terminated hyperbranched polymer crosslinking agent were sequentially added dropwise to a homogeneous phase of a nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction was induced between the amino-terminated groups and the isocyanate groups in the prepolymer to obtain a highly active weather-resistant coating stock solution with self-leveling properties. The highly active weather-resistant coating solution is uniformly coated onto the surface of a railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, and a step-induced thermo-crosslinking curing treatment is performed according to a preset procedure to promote the formation of an interpenetrating network structure of fluorosilicone modified nanophase and polymer organic phase inside the coating system, and the weather-resistant railway turnout coating is formed in situ cured on the surface of the metal substrate.

[0007] Optionally, the step of subjecting the graphene oxide dispersion to a fluorinated polyether silane coupling agent via ultrasonic cavitation and covalent grafting in an acidic alcohol-water medium to obtain fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups includes: A monolayer exfoliated graphene oxide powder with controlled lateral dimensions and thickness and a predetermined defect ratio was prepared and dispersed in ultrapure water to form a graphene oxide dispersion with a specific structure. Deionized water and anhydrous ethanol were mixed, and phytic acid and trifluoroacetic acid were added to adjust the polarity and pH value, thus preparing a composite acidic alcohol-water medium. Fluorinated polyether silane coupling agent is pumped into a composite acidic alcohol-water medium at a constant rate and mixed with a graphene oxide dispersion with a specific structure. The covalent grafting reaction is stimulated under an asymmetric dual-frequency pulsed ultrasonic field and stepped temperature control to form a fluorosilane-modified graphene oxide slurry. The fluorosilane-modified graphene oxide slurry was subjected to centrifugal washing and freeze-drying to remove the solvent, resulting in fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups.

[0008] Optionally, the stepwise temperature-increasing polymerization reaction of aliphatic diisocyanate, polytetrafluoroethylene glycol, and polycarbonate glycol under inert gas protection and in the presence of a catalyst to synthesize a weather-resistant polyurethane prepolymer with fluorinated main chain blocks and isocyanate end groups includes: The selected polycarbonate diol and polytetrafluoroethylene diol were subjected to extreme dehydration treatment under constant temperature and vacuum conditions to obtain anhydrous macromolecular diol raw materials with a moisture content lower than a preset threshold. Adding trace amounts of non-toxic organic bismuth-zinc complex isooctanoate to aliphatic diisocyanate mixed monomers forms a highly efficient synergistic catalytic isocyanate system. Under the protection of high-purity nitrogen, the highly efficient synergistic catalytic isocyanate system is mixed with polytetrafluoroethylene glycol in anhydrous macromolecular diol raw material and reacted at a first set temperature to generate fluorine-rich micro-region preblocks. Polycarbonate diol from anhydrous macromolecular diol raw material was added dropwise at a uniform rate to a fluorine-rich micro-region preblock, and in-situ block copolymerization was carried out by smooth heating. The prepolymer was then cooled and vacuum-cured to synthesize a weather-resistant polyurethane prepolymer with fluorine-containing main chain blocks and isocyanate-terminated end groups.

[0009] Optionally, the addition of fluorosilane-modified graphene oxide nanosheets to the weather-resistant polyurethane prepolymer at a predetermined mass fraction, followed by multi-stage gradient temperature-controlled mixing using a vacuum high-shear emulsifier, allows the nanosheets to form an isotropic three-dimensional network dispersion structure within the prepolymer matrix, resulting in a homogeneous nanocomposite prepolymer phase, comprising: A low-boiling-point, non-active, environmentally friendly diluent was sprayed onto fluorosilane-modified graphene oxide nanosheets and then subjected to low-speed planetary stirring under vacuum to allow the fluoroalkyl groups on the surface to spread, resulting in an interface-preactivated nanosheet slurry. The interface pre-activated nanosheet slurry is rapidly pumped into the main emulsification kettle containing the weather-resistant polyurethane prepolymer at a set temperature. Under extreme vacuum, the first stage of high-speed high-frequency crushing and mixing is performed to force the tearing of the aggregates, forming a submicron-level forced dispersion initial mixed phase. The submicron-level forced dispersion initial mixed phase is subjected to a second stage of medium-speed homogenization and temperature-controlled mixing to induce trace interfacial grafting between surface-active silanol groups and terminal isocyanate groups, forming an interfacial anchored semi-homogeneous phase. A third-stage low-speed curing and cooling mixing process was performed on the interface-anchored semi-homogeneous phase to promote the self-assembly and relaxation of polymer chain segments to construct a three-dimensional network dispersion structure, thereby obtaining a nanocomposite prepolymer homogeneous phase with thixotropic properties.

[0010] Optionally, the hindered amine light stabilizer presolvent and the terminal amino hyperbranched polymer crosslinking agent are sequentially added dropwise to the homogeneous phase of the nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction is induced between the terminal amino groups and the isocyanate groups in the prepolymer to obtain a highly active weather-resistant coating stock solution with self-leveling properties, comprising: Etherified hindered amine light stabilizers were completely dissolved in a mixture of polar and nonpolar solvents and degassed by ultrasonication in the dark to obtain molecularly deassociated hindered amine light stabilizer presolvents. Under a constant mechanical stirring shear field, the hindered amine light stabilizer presolvent is added dropwise to the isothermal homogeneous phase of the nanocomposite prepolymer, and is locked in the interchain gap by hydrogen bonding and conjugation to form a light stabilizer embedded homogeneous phase. Spherical terminal amino hyperbranched polymer crosslinking agent was atomized and sprayed into a homogeneous phase embedded with a light stabilizer to induce a rapid nucleophilic addition reaction between the terminal amino groups and isocyanate groups, thus constructing a microscopic star-shaped-linear pre-interpenetrating network prototype. The apparent viscosity of the microscopic star-shaped-linear pre-interpenetrating network prototype is monitored online. When the viscosity smoothly rises to the preset target range, the water bath temperature is immediately reduced and the stirring speed is slowed down to freeze the crosslinking reaction, thus obtaining a highly active weather-resistant coating stock solution with self-leveling properties.

[0011] Optionally, the step of uniformly coating the highly active weather-resistant coating solution onto the surface of a railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, and performing a preset procedure of stepped thermo-induced crosslinking curing treatment, promotes the formation of an interpenetrating network structure of fluorosilicone modified nanophase and polymeric organic phase within the coating system, and cures in situ on the surface of the metal substrate to form the weather-resistant railway turnout coating, includes: High-pressure airflow mixed with brown corundum abrasive is used to perform multi-angle sandblasting roughening of railway turnout metal substrates, remove the passivation layer and expose free metal hydroxyl groups, and obtain highly active metal substrates with specific micro-roughness. The highly active weather-resistant coating stock solution is uniformly sprayed onto the surface of the highly active metal substrate, and the preset wet film thickness is controlled to form a highly active wet film coating. The highly active wet film coating is placed in a low-humidity infrared environment to perform the first stage of mild thermal curing, driving the fluorine-containing components to migrate to the surface and self-assemble on the polar surface to form a superhydrophobic fluorine-containing armor layer. The coating system with a superhydrophobic fluorine-containing armor layer is subjected to a second stage of gradual temperature rise curing to awaken the residual amino groups of the hyperbranched crosslinking agent to carry out deep crosslinking in order to build a dense polymer skeleton and form a deep crosslinking transition coating. The deep cross-linked transition coating is subjected to a third stage of high-temperature baking and locking, which forces the inorganic nanophase domain and the pure organic phase domain to become extremely entangled. Finally, the stress is released by slow cooling, and the weather-resistant railway turnout coating is formed in situ on the surface of the metal substrate.

[0012] A weather-resistant railway turnout coating is characterized in that, after the coating is cured into a film, it has an isotropic three-dimensional network dispersed microstructure and a gradient phase separation configuration in the thickness direction.

[0013] The beneficial effects of this invention are: This invention utilizes asymmetric dual-frequency ultrasonic cavitation in an acidic alcohol-water medium to covalently graft nanosheets, and employs a high-power stator-rotor system for high-frequency forced shearing under an ultimate vacuum below 500 Pascals. This completely breaks the thermodynamic agglomeration tendency of nanomaterials in polar polymer melts, constructing an isotropic three-dimensional network dispersion structure in situ within a prepolymer matrix. Through the synergistic effect of fluoroalkyl group expansion pre-activation and high-frequency shear tearing, supplemented by medium-speed homogenization and temperature control, this invention ensures precise micro-interfacial in-situ grafting between nanosheets and polymer segments, significantly improving the rheological stability and extremely high thixotropy of the nanocomposite system.

[0014] This invention utilizes a stepwise temperature-controlled polymerization process with a trace amount of non-toxic organic bismuth-zinc composite catalyst to synthesize a prepolymer with fluorinated main-chain blocks and isocyanate end groups. This process induces rapid nucleophilic addition between the isocyanate groups and highly branched terminal amino groups within the system, constructing a microscopic star-shaped-linear pre-interpenetrating network. Hydrogen bonds and conjugation tightly embed and lock the deassociated light stabilizer molecules within the inter-chain spaces of the polymer. By introducing entanglement-free three-dimensional spherical hyperbranched crosslinking hubs, this invention provides extremely high crosslinking density potential while maintaining excellent self-leveling and spreading properties. This completely blocks the thermodynamic path of light stabilizer precipitation, resulting in significantly improved resistance to degradation under conditions of high-frequency vibration and strong ultraviolet radiation combined fatigue.

[0015] This invention combines a pre-programmed stepped thermo-induced crosslinking curing process with a gently controlled temperature gradient to precisely induce the rearrangement evolution of the nanophase and organic phases within the coating system. Utilizing the ample thermodynamic time of a mild volatilization period, it drives the large-scale targeted migration of extremely low surface energy fluorinated components to the coating-air interface. At high temperatures, it forces extremely dense entanglement between the inorganic nanophase domains and the pure organic phase domains, predicting and controlling the gradient structural evolution of the coating from a superhydrophobic surface to a highly adhesive substrate. This balances the surface's water and oil repellency and self-cleaning properties with the substrate's impact-resistant cohesiveness. The multidimensional curing mechanism of this invention utilizes the deep crosslinking of residual amino groups and the reaction with interfacial metal hydroxyl groups to completely cure and form an irreversible organic-inorganic semi-interpenetrating network structure. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart illustrating a weather-resistant railway turnout coating and its preparation method, as proposed in this invention. Detailed Implementation

[0017] Example 1: Reference Figure 1A method for preparing a weather-resistant railway turnout coating, the method comprising: A dispersion of graphene oxide was subjected to ultrasonic cavitation and covalent grafting reaction with a fluorinated polyether silane coupling agent in an acidic alcohol-water medium to obtain fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups. In this embodiment, a graphene oxide dispersion and a fluorinated polyether silane coupling agent are subjected to ultrasonic cavitation and covalent grafting reactions in an acidic alcohol-water medium to obtain fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups, comprising: A graphene oxide dispersion with a specific sheet size and defect ratio was prepared by dispersing monolayer exfoliated graphene oxide powder synthesized by a modified Hummers method in ultrapure water. The average lateral size of the monolayer exfoliated graphene oxide was precisely controlled between 0.8 μm and 1.5 μm, and the thickness range measured by atomic force microscopy was strictly limited to 0.9 nm to 1.2 nm. Furthermore, the intensity ratio of the D peak to the G peak, which characterizes structural defects, in the Raman spectrum was precisely within a narrow window of 1.05 to 1.15, which exposed the highest density of oxygen-containing functional groups such as carboxyl, hydroxyl, and epoxy groups at the sheet edges and surface. An environmentally friendly acidic alcohol-water medium with synergistic catalytic effect was constructed, abandoning traditional highly toxic organic solvents and volatile inorganic strong acids. Deionized water and anhydrous ethanol were mixed at a volume ratio of 1:3 to 1:4 as a polar base solvent. Naturally extracted polyhydroxy phytic acid and trace amounts of trifluoroacetic acid were introduced as composite acid regulators and catalysts. The pH value of the acidic alcohol-water medium was extremely narrowed and locked in the critical range of 3.50 to 3.85. Phytic acid not only provides protons to catalyze the incomplete hydrolysis of silanes, but its multiple phosphate groups can also form a steric chelate layer with residual metal ions at the edge of graphene oxide, preventing the secondary aggregation of nanosheets under subsequent high-energy fields. An asymmetric dual-frequency ultrasonic cavitation and gradient drop covalent grafting process was employed. Fluorinated polyether silane coupling agents with a molecular weight between 800 and 1200 were pumped into a prepared acidic alcohol-water medium system at a constant rate of 2.5 to 3.5 ml per minute. Simultaneously with the pumping and for 120 minutes after the pumping was completed, an asymmetric dual-frequency pulsed ultrasonic field was applied. The ultrasonic field consisted of alternating outputs from a low-frequency generator with a fundamental frequency of 28 kHz and a high-frequency generator with a fundamental frequency of 40 kHz. The low-frequency ultrasound, with a power density of 850 W, dominated the generation of large bubble bursts and cavitation to strongly peel off and disperse the nanosheets. The high-frequency ultrasound, with a power density of 450 W, dominated the generation of microjets to greatly increase the effective collision probability between the silanol groups generated by the hydrolysis of the fluorinated polyether silane coupling agent and the hydroxyl groups on the surface of graphene oxide. The ultrasonic pulses used a duty cycle of 3 seconds of operation and 2 seconds of interruption to avoid silane self-condensation caused by local overheating. Throughout the ultrasonic cavitation process, an intelligent temperature-controlled jacket was used to control the temperature of the reaction system in a stepwise manner: for the first 40 minutes, the temperature was maintained at 25°C to 30°C to induce the hydrolysis of the coupling agent; for the middle 40 minutes, the temperature was programmed to rise to 55°C to 60°C to activate the covalent grafting reaction of dehydration condensation; and for the last 40 minutes, the temperature was lowered to 15°C to quench the side reactions. After high-speed centrifugation, washing, and freeze-drying, fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups were obtained. X-ray photoelectron spectroscopy showed that the atomic molar percentage of fluorine on the surface was precisely anchored in the ultra-high grafting range of 15.5% to 18.2%, while retaining a sufficient density of uncondensed active silanol groups, providing an ideal topological interface basis for subsequent chemical anchoring in a polyurethane matrix.

[0018] Under the protection of an inert gas and in the presence of a catalyst, aliphatic diisocyanate, polytetrafluoroethylene glycol and polycarbonate glycol were subjected to a stepwise heating polymerization reaction to synthesize a weather-resistant polyurethane prepolymer with fluorinated main chain blocks and isocyanate end groups. In this embodiment, under the protection of an inert gas and in the presence of a catalyst, aliphatic diisocyanate, polytetrafluoroethylene glycol, and polycarbonate glycol are subjected to a stepwise temperature-increasing polymerization reaction to synthesize a weather-resistant polyurethane prepolymer with fluorinated main chain blocks and isocyanate end groups, comprising: In terms of precise selection and pretreatment of reaction raw materials, the aliphatic diisocyanate selected was a mixed monomer composed of isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate in a molar ratio of 2:1. The asymmetric reactivity of the primary and secondary isocyanate groups of IPDI was used to control the regularity of the main chain formation. Polycarbonate diol with a number average molecular weight of 2000 was selected as the soft segment host to provide UV resistance and hydrolysis resistance, and dihydroxy-terminated polytetrafluoroethylene diol with a number average molecular weight of 1000 was selected as the fluorinated soft segment to impart extremely low surface energy and weather resistance. Before the reaction, PCDL and PTFE-diol were placed in a constant temperature vacuum dehydration kettle and treated for 4 hours under extreme dehydration conditions of negative pressure -0.098 MPa and 110 degrees Celsius to ensure that the moisture content of the system was strictly below 0.02% to prevent the consumption of isocyanate groups by side reactions. A novel, non-toxic, and environmentally friendly non-tin catalyst was employed, completely abandoning dibutyltin dilaurate, which is prone to causing corrosion of the galvanic cell in turnout metal substrates and is highly toxic to the environment. A newly synthesized organic bismuth-zinc composite isooctanoate catalyst was used, in which the bismuth metal center and the zinc metal center exhibit unprecedented synergistic catalytic selectivity for the urethane formation reaction of isocyanate and hydroxyl groups through a polynuclear complexation effect in three-dimensional space. This not only increases the conversion rate of the main reaction to over 99.5%, but also significantly increases the activation energy of the urea carbamate side reaction that leads to cross-linking gels, fundamentally locking in the occurrence pathway of the side reaction. The amount of composite catalyst added is extremely small, only 0.03% to 0.05% of the total resin mass. A high-precision three-stage stepped heating in-situ block copolymerization process was employed, under continuous dynamic purging protection with 99.999% pure nitrogen: In the first reaction stage, aliphatic diisocyanate mixed monomers, calculated to maintain the molar ratio of isocyanate groups to total hydroxyl groups in the total system precisely between 1.85 and 2.05, were added to the reactor. After adding a non-toxic catalyst, polytetrafluoroethylene glycol was added dropwise extremely slowly at 65 degrees Celsius over a period of 2 hours, followed by a 1.5-hour holding period. At this point, taking advantage of the relatively low steric hindrance, the highly hydrophobic fluorinated macromolecular diol is forced to preferentially react with isocyanate to form fluorine-rich micro-blocks. In the second reaction stage, the temperature is smoothly increased to 85 degrees Celsius at an ultra-low rate of 0.5 degrees Celsius per minute, and polycarbonate diol is added dropwise at a uniform rate. The reaction is maintained at this temperature for 2.5 hours, allowing the non-fluorinated weather-resistant soft segments to be seamlessly embedded into the main chain backbone. In the third reaction stage, the temperature is lowered to 70 degrees Celsius, a vacuum is drawn to remove trace amounts of gas, and the mixture is stabilized for 1 hour. By using a specific reaction sequence and a breakthrough catalytic system based on the selected invention, a product was successfully synthesized that exhibits high transparency on a macroscopic scale, clear separation of fluorocarbon soft segments and carbonate soft segments on a microscopic scale, and an extremely narrow molecular weight distribution. The mass fraction of free -NCO in the system was stable at 4.5% to 5.2%, resulting in a weather-resistant polyurethane prepolymer with an impeccable main chain block containing fluorine and isocyanate end groups.

[0019] Fluorosilane-modified graphene oxide nanosheets were added to a weather-resistant polyurethane prepolymer at a predetermined mass fraction. The nanosheets were then mixed using a vacuum high-shear emulsifier with a multi-stage gradient temperature control to form an isotropic three-dimensional network dispersion structure in the prepolymer matrix, thus obtaining a homogeneous phase of the nanocomposite prepolymer. In this embodiment, fluorosilane-modified graphene oxide nanosheets are added to a weather-resistant polyurethane prepolymer at a predetermined mass fraction. Multi-stage gradient temperature-controlled mixing is then performed using a vacuum high-shear emulsifier to form an isotropic three-dimensional network dispersion structure of the nanosheets within the prepolymer matrix, resulting in a homogeneous nanocomposite prepolymer phase, comprising: To avoid introducing a large amount of air bubbles into the high-viscosity prepolymer, the degassing, pre-wetting, and interface activation treatment of the nanosheets involved extracting fluorosilane-modified graphene oxide nanosheets at a predetermined mass fraction and placing them in a sealed, explosion-proof homogenizing tank. A low-boiling-point, non-reactive, environmentally friendly diluent, accounting for 15% to 20% of the nanosheet mass, was pre-sprayed and then subjected to low-speed planetary stirring for 30 minutes under a vacuum of -0.08 MPa. This allowed the solvent molecules to fully penetrate the interlayer gaps of the graphene oxide nanosheets, not only expelling the adsorbed trace amounts of air but also causing the fluoroalkyl segments grafted onto the nanosheet surface to exhibit an extended tentacle-like morphology under solvation, thus completing the crucial interface pre-activation. Under dynamic vacuum, a high-power stator-rotor forced shear mixing process is used to rapidly pump the activated nanosheet slurry through a sealed negative pressure suction pipe into a main emulsification vessel containing weather-resistant polyurethane prepolymer heated to 60 degrees Celsius. The stator-rotor high-shear emulsification machine system with a special tooth structure is started. Under an ultimate vacuum environment where the absolute pressure is maintained below 500 Pascals, the first stage of high-frequency crushing and mixing is performed. The rotor speed is instantly increased and locked in the ultra-high shear rate range of 8000 rpm to 10000 rpm for an extremely short duration of 15 to 20 minutes. The extremely large hydrodynamic shear stress generated by the ultra-narrow gap of only 0.2 mm between the stator and rotor is used to forcibly tear the macroscopic aggregates of nanosheets into single-sheet or few-layer structures. The ultimate vacuum state ensures that the microbubbles generated under such intense friction are immediately extracted, avoiding the local thermal degradation problem caused by ultrasonic dispersion. The multi-stage gradient decreasing temperature-controlled mixing process, controlled by topological evolution and rheology, immediately enters the programmed relaxation and chemical anchoring stage after the first stage of forced dispersion. The second stage, medium-speed homogenization, involves slowly raising the main vessel temperature to 75 degrees Celsius, rapidly reducing the high-shear rotation speed to 3500 rpm, and simultaneously activating a slow-speed wall-scraping stirrer for 45 minutes. Under the combined effect of this temperature and medium shear force, residual active silanol groups on the nanosheet surface undergo a small amount of in-situ interfacial grafting reaction with some isocyanate groups at the prepolymer ends, completely blocking the thermodynamic tendency of secondary agglomeration of the nanosheets. The third stage, low-speed ripening, involves lowering the temperature to 50 degrees Celsius, shutting off the high-shear operation, and retaining only 20 rpm of anchor stirring for 60 minutes, allowing the polymer chains to self-assemble and relax after the shear stress is removed. Through extremely stringent rheological control and thermodynamic induction, the nanosheets do not float randomly in the prepolymer matrix. Instead, they spontaneously construct a microscopically isotropic three-dimensional network dispersion structure with completely consistent physical properties in all macroscopic directions through fluorine-fluorine hydrophobic interactions, interfacial chemical bonding, and physical entanglement of polymer chains. At this point, the rheological characteristics of the system undergo a qualitative leap, exhibiting extremely strong thixotropy, thus obtaining an extremely stable homogeneous phase of nanocomposite prepolymer without any flaws.

[0020] A hindered amine light stabilizer presolvent and an amino-terminated hyperbranched polymer crosslinking agent were sequentially added dropwise to a homogeneous phase of a nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction was induced between the amino-terminated groups and the isocyanate groups in the prepolymer to obtain a highly active weather-resistant coating stock solution with self-leveling properties. In this embodiment, a hindered amine light stabilizer presolvent and a terminal amino hyperbranched polymer crosslinking agent are sequentially added dropwise to a homogeneous phase of a nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction is induced between the terminal amino groups and the isocyanate groups in the prepolymer, resulting in a highly active weather-resistant coating stock solution with self-leveling properties, comprising: A seamless interlocking structure of hindered amine light stabilizers and a special crosslinking system, previously unreported in this field, was designed and synthesized. First, a specific hindered amine light stabilizer pre-solvent was prepared: an etherified hindered amine light stabilizer with low alkalinity and low susceptibility to side reactions with isocyanates was selected and completely dissolved at a mass concentration of 10% in a mixed solvent of anhydrous propylene glycol methyl ether acetate and xylene. Ultrasonic degassing was then performed under light-protected conditions to ensure complete deassociation of the light stabilizer at the molecular level. Next, a breakthrough crosslinking agent was introduced: abandoning traditional linear small-molecule chain extenders, a third-generation spherical terminal amino hyperbranched polymer was adopted as the core crosslinking hub. The hyperbranched polymer uses pentaerythritol as its core backbone, with 16 to 24 highly reactive primary amino groups densely distributed around it. The unique highly branched, non-entangled three-dimensional spherical molecular conformation endows the system with extremely low melt viscosity while providing an astonishingly high potential for crosslinking density. In the core operation process, the temperature of the homogeneous phase of the nanocomposite prepolymer is precisely kept constant at 35 degrees Celsius in a constant temperature water bath reactor equipped with a high-precision torque sensor. Under a constant mechanical stirring shear field of 250 rpm, the hindered amine light stabilizer presolvent is added to the homogeneous phase at an extremely slow rate of 2 drops per minute using a high-pressure micro-metering pump. The mixture is stirred continuously for 30 minutes, so that the light stabilizer molecules are uniformly embedded and locked in the polymer chain gaps of the prepolymer by means of π-π conjugation and hydrogen bonding with the polar groups in the homogeneous phase, preventing them from being precipitated and lost on the surface under long-term ultraviolet exposure in the later stage. Entering the critical step of mild pre-crosslinking that determines the film-forming properties, the water bath temperature is kept absolutely stable at 35 degrees Celsius. The calculated amount of terminal amino hyperbranched polymer crosslinking agent is evenly sprayed into the reaction system through atomizing nozzles with micron-sized pores. Since the reaction rate between alicyclic amino groups and isocyanates is extremely fast, it is necessary to use high-intensity turbulent stirring at 500 rpm to dissipate the local reaction heat instantly. This induces several terminal amino groups around the spherical hyperbranched crosslinking agent to preferentially undergo rapid nucleophilic addition reactions with the isocyanate groups at the ends of the linear polyurethane prepolymer, forming urea bond nodes with strong cohesive force. By precisely capturing the endpoint of mild pre-crosslinking through online monitoring of torque changes, when the Brookfield apparent viscosity of the reactant system smoothly rises to the golden range of 4500 mPa·s to 5500 mPa·s, the water bath temperature is immediately and drastically reduced to 15 degrees Celsius and the stirring speed is slowed to 50 rpm to freeze the reaction progress. At this point, a microscopic star-shaped-linear pre-interpenetrating network with hyperbranched polymers as the core has been formed in the system, but it still maintains excellent fluidity on a macroscopic scale. This gives the material excellent leveling and spreading ability within 30 minutes after shearing stops, resulting in a highly active weather-resistant coating concentrate that exhibits perfect self-leveling properties in on-site construction. The highly active weather-resistant coating solution is uniformly coated onto the surface of the railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, and a step-induced thermal crosslinking curing treatment is performed according to a preset procedure to promote the formation of an interpenetrating network structure of fluorosilicone modified nanophase and polymer organic phase inside the coating system, and the weather-resistant railway turnout coating is formed in situ cured on the surface of the metal substrate.

[0021] In this embodiment, a highly active weather-resistant coating stock solution is uniformly coated onto the surface of a railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, and a preset program of stepped thermo-crosslinking curing treatment is performed to promote the formation of an interpenetrating network structure of fluorosilicone modified nanophase and polymer organic phase within the coating system. This results in in-situ curing of a weather-resistant railway turnout coating on the metal substrate surface, including: In terms of interface pretreatment for in-situ coating film formation, extremely stringent surface lattice activation and microtexturing were carried out on the high-manganese steel substrate of railway turnouts subjected to high-frequency mechanical impact and complex climate alternation environment. Brown corundum abrasive with a hardness of Mohs 9 was used to perform multi-angle sandblasting roughening operation under a stable high-pressure airflow of 0.6 MPa to 0.8 MPa. The surface roughness Ra value of the substrate was precisely controlled between 45 micrometers and 60 micrometers, and the Rz value was controlled between 120 micrometers and 150 micrometers. This level of micro-barbed peak and valley morphology not only provides a large mechanical interlocking surface area, but more importantly, it removes the passivation layer of the metal surface, exposing fresh crystal faces with high surface energy and free iron / manganese hydroxyl groups. On this highly active surface, the highly active weather-resistant coating liquid was uniformly coated using an airless spraying equipment, and the wet film thickness was strictly controlled between 350 micrometers and 400 micrometers. Most importantly, the innovative pre-programmed stepped thermo-crosslinking curing process represents the pinnacle of the simultaneous interplay between microscopic phase separation and macromolecular topological locking: In the first curing stage, the coated turnout substrate is placed in an infrared curing chamber with a relative humidity of less than 30%, and the temperature is set at 40 degrees Celsius and maintained for up to 120 minutes. This mild stage avoids coating pores caused by rapid solvent boiling, while providing the system with ample thermodynamic time. The introduced fluorosilane-modified graphene oxide nanosheets and perfluoropolyether soft segments in the prepolymer undergo large-scale targeted migration and directional rearrangement towards the coating-air interface under the spontaneous driving force of thermodynamically reducing the system's free energy. This results in the self-assembly of a superhydrophobic fluorinated armor layer with a thickness of several micrometers, characterized by extremely low surface energy and high water and oil repellency. In the second curing stage, the temperature is gradually increased to 85 degrees Celsius at a rate of 2 degrees Celsius / minute and maintained at a constant temperature for 180 minutes. Under this thermal field, the free isocyanate groups reserved in the early stage begin to undergo intense covalent chemical bonding with the moisture that permeates in the air and the metal hydroxyl groups on the surface of the substrate. At the same time, the residual amino groups with large steric hindrance inside the terminal amino hyperbranched polymer are completely awakened and undergo a deep cross-linking curing reaction, thus constructing a dense polymer skeleton with both rigidity and flexibility in the lower layer of the coating. In the third curing stage, the temperature is further increased to 120 degrees Celsius for a short-term high-temperature baking of 60 minutes. The physical interpenetration in the early stage and the chemical cross-linking in the later stage reach their extreme, forcing the inorganic nanophase domains containing fluorine / silicon and the pure organic phase domains of polyurethane / polycarbonate to form extremely dense entanglement at the nanoscale. This completely cures and forms an irreversible organic-inorganic semi-interpenetrating network structure with thermodynamic metastable state. The structure is then naturally cooled to room temperature at an extremely slow cooling curve of no more than 1 degree Celsius / minute to release the internal stress caused by curing shrinkage. A weather-resistant railway turnout coating with resistance to ultraviolet aging, ultra-high wear resistance, and excellent resistance to temperature difference cracking is generated in situ on the surface of the metal substrate.

[0022] Example 2: In the laboratory solution preparation stage, the experimenter extracted a batch of monolayer exfoliated graphene oxide powder synthesized by the modified Hummers method. Atomic force microscopy measurements showed that the average lateral dimension of the powder was 1.2 micrometers, and the thickness was 1.0 nanometers. Raman spectroscopy determined the intensity ratio of its D peak to G peak to be 1.12. The experimenter then dispersed the powder in ultrapure water.

[0023] In an acidity adjustment tank, the experimenter mixed deionized water and anhydrous ethanol at a volume ratio of 1:3.5, and slowly added phytic acid and trifluoroacetic acid. During this process, the pH meter monitored the acidity of the solution in real time. When the reading stabilized at 3.65, the addition was stopped, resulting in a composite acidic alcohol-water medium.

[0024] In the reactor, the operator activated a high-precision horizontal pump to inject 1000 molecular weight perfluoropolyether segment-terminated triethoxysilane into the medium at a precise flow rate of 3.0 mL / min. Simultaneously, the system triggered an asymmetric dual-frequency pulsed ultrasonic field. The instrument panel displayed: low-frequency end frequency 28 kHz, output power 850 W; high-frequency end frequency 40 kHz, output power 450 W; duty cycle strictly adhering to 3 seconds of operation followed by 2 seconds of rest. The temperature control probe recorded the entire temperature trajectory: maintaining 28°C for the first 40 minutes, then rising at a constant rate to 58°C and maintaining it for 40 minutes, finally dropping sharply to 15°C within 10 minutes and maintaining it for 30 minutes. After centrifugation and freeze-drying, X-ray photoelectron spectroscopy (XPS) analysis showed that the atomic molar percentage of fluorine on the product surface reached 16.8%, successfully obtaining fluorosilane-modified graphene oxide nanosheets.

[0025] II. Catalytic and Temperature Control Parameters in the Prepolymer Synthesis Stage In the polyurethane synthesis workshop, operators handle soft-segment macromolecules. Polycarbonate glycol with a number average molecular weight of 2000 and polytetrafluoroethylene glycol with a number average molecular weight of 1000 are placed in a dehydration reactor. The vacuum pressure is reduced to -0.098 MPa, and the oil bath temperature is raised to 110°C and maintained for 4 hours. Multiple samples are taken using a Karl Fischer moisture analyzer, confirming that the system moisture content has decreased to 0.015%, meeting the critical reaction requirements.

[0026] Inside the reactor, the operator mixed isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate at a molar ratio of 2:1, with the NCO / OH index set to 1.95. Subsequently, an organobismuth-zinc composite isooctanoate catalyst, comprising 0.04% of the total resin weight, was injected using a microsyringe.

[0027] High-purity nitrogen was continuously purged at a flow rate of 500 mL / min. When the thermometer showed the internal temperature reached 65°C, polytetrafluoroethylene glycol was added dropwise over 2 hours, followed by a 1.5-hour holding period. The temperature control system then increased the temperature to 85°C at a ramp rate of 0.5°C / min. Polycarbonate diol was then added dropwise at a uniform rate and held at this temperature for 2.5 hours. Finally, the temperature was lowered to 70°C and a vacuum was applied for 1 hour. Gel chromatography showed a polydispersity index (PDI) of 1.38, and chemical titration showed a stable free NCO content of 4.8%, indicating that the prepolymer synthesis met the standards.

[0028] III. Implementation Parameters for Rheological Control in the Forced Shear Mixing Stage Upon entering the material mixing zone, the operator weighs 1.0% of the aforementioned modified nanosheets by mass of the prepolymer and sprays 18% of the nanosheets by mass of dimethyl carbonate. The material is then fed into a planetary mixer, which operates for 30 minutes under a vacuum of -0.08 MPa at a revolution speed of 15 rpm and a rotation speed of 30 rpm to complete the wetting and activation of the nanosheet interfaces.

[0029] The activated slurry was instantly drawn into the main reactor containing 60°C prepolymer through a negative pressure pipeline. The vacuum pump operated at full load, reducing the absolute pressure inside the reactor to 450 Pascals. The operator then revved the high-shear emulsifier to its maximum speed of 9000 rpm, and the equipment ran under extremely high load for 18 minutes.

[0030] The control system automatically executed the degradation command: the main vessel temperature rose to 75℃, the high-shear rotation speed was abruptly reduced to 3500 rpm, and a wall-scraping agitator at 40 rpm was simultaneously activated for 45 minutes. Infrared spectroscopy analysis of the samples showed an interfacial grafting rate of 2.5%. In the final stage, the temperature dropped to 50℃, the high-shear rotation was shut off, and only anchor stirring at 20 rpm was maintained for 60 minutes of maturation. The thixotropic index of the system measured by the rheometer reached 4.8, indicating a perfectly isotropic dispersion of the slurry.

[0031] IV. Implementation parameters for online viscosity capture during the pre-crosslinking stage of amino-terminated amino groups In a constant-temperature water bath reactor, the operator first prepared a 10% (w / w) TINUVIN 123 pre-solvent. When the main reactor water bath temperature sensor accurately reached 35.0°C, the stirrer was operated at 250 rpm. A micro-metering pump dripped the pre-solvent into the reactor at a rate of 2 drops / minute for 30 minutes.

[0032] The operator set the molar ratio of total amino groups to NCO groups to 0.92:1 for the terminal amino hyperbranched polymer, and sprayed it into the system through a micron-level atomizing nozzle, while simultaneously increasing the stirring speed to 500 rpm for forced heat dissipation. The technician's eyes were fixed on the screen of the online Brookfield viscometer. The viscosity curve on the screen began to climb non-linearly as the reaction proceeded: 2000... 3500... 4800. The moment the reading reached 5100 mPa·s, the operator decisively pressed the emergency stop button and triggered the cooling program. Cooling water was rapidly injected into the jacket, and the system temperature was forcibly pulled down to 15°C within 3 minutes, with the stirring speed reduced to 50 rpm. The highly reactive weather-resistant coating stock solution was successfully frozen within an excellent self-leveling state window.

[0033] V. Implementation parameters for separating on-site construction and stepped curing At the railway turnout construction site, the engineering team started a high-power, high-pressure air compressor. A sandblasting gun sprayed brown fused alumina abrasive with a Mohs hardness of 9 at a stable pressure of 0.7 MPa. After grinding, a portable roughness tester measured the substrate surface surface Ra value at 52 micrometers and the Rz value at 135 micrometers. The construction workers then applied the undiluted solution using airless spraying, and a wet film thickness gauge took multiple samples to confirm that the coating thickness was controlled at approximately 380 micrometers.

[0034] The mobile infrared tunnel curing oven was pushed into the track. The curing process was executed strictly according to the settings: Phase 1: The relative humidity in the curing chamber is controlled at 25%, and the infrared probe maintains the coating surface temperature at 40°C for 120 minutes. During this phase, the low surface energy fluorosilicone components float to the surface.

[0035] The second stage: The PLC control board steadily raises the temperature to 85℃ at a heating rate of 2℃ / minute, and holds it at a constant temperature for 180 minutes to promote deep cross-linking between the underlying amino group and the substrate.

[0036] Third stage: The temperature jumps to 120℃ for a final 60-minute intensive baking.

[0037] With the heat source cut off, the equipment cools naturally to room temperature at a rate of approximately 0.8°C / minute.

[0038] VI. Implementation Data and Anomaly Interception Feedback On the 7th day after the coating was fully cured, the testing center conducted destructive sampling tests on the test panels laid on site. The universal testing machine measured the adhesion to be as high as 23.1 MPa, with the fracture surface entirely located deep within the coating and no detachment at the metal interface. The Taber abrasion test using a CS-17 rubber abrasive wheel showed a mass loss of only 9.2 mg, and the water contact angle meter showed an initial surface contact angle of 118°.

[0039] It is worth mentioning that during the second phase of this project, the infrared online moisture monitoring system issued a weak warning: due to a sudden change in the humidity of the workshop environment, the moisture reading in the dehydration vessel fluctuated by 0.025%. The system immediately activated the vacuum pump to increase the pumping power, and only allowed the electronic command to send "catalyst addition permitted" to the main reactor after the Karl Fischer moisture meter reading fell back to the threshold of 0.015%. This closed-loop control effectively avoided urea bond side reactions caused by trace amounts of moisture, ensuring the purity of the final macromolecular topological network.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a weather-resistant railway turnout coating, characterized in that, The preparation method includes: A dispersion of graphene oxide was subjected to ultrasonic cavitation and covalent grafting reaction with a fluorinated polyether silane coupling agent in an acidic alcohol-water medium to obtain fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups. Under the protection of an inert gas and in the presence of a catalyst, aliphatic diisocyanate, polytetrafluoroethylene glycol and polycarbonate glycol were subjected to a stepwise heating polymerization reaction to synthesize a weather-resistant polyurethane prepolymer with fluorinated main chain blocks and isocyanate end groups. Fluorosilane-modified graphene oxide nanosheets were added to the weather-resistant polyurethane prepolymer at a predetermined mass fraction, and multi-stage gradient temperature-controlled mixing was carried out using a vacuum high-shear emulsifier to form an isotropic three-dimensional network dispersion structure of the nanosheets in the prepolymer matrix, thereby obtaining a homogeneous phase of nanocomposite prepolymer. A hindered amine light stabilizer presolvent and an amino-terminated hyperbranched polymer crosslinking agent were sequentially added dropwise to a homogeneous phase of a nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction was induced between the amino-terminated groups and the isocyanate groups in the prepolymer to obtain a highly active weather-resistant coating stock solution with self-leveling properties. The highly active weather-resistant coating solution is uniformly coated onto the surface of a railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, and a step-induced thermo-crosslinking curing treatment is performed according to a preset procedure to promote the formation of an interpenetrating network structure of fluorosilicone modified nanophase and polymer organic phase inside the coating system, and the weather-resistant railway turnout coating is formed in situ cured on the surface of the metal substrate.

2. The method for preparing a weather-resistant railway turnout coating according to claim 1, characterized in that, The process of reacting a graphene oxide dispersion with a fluorinated polyether silane coupling agent via ultrasonic cavitation and covalent grafting in an acidic alcohol-water medium yields fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups, comprising: A monolayer exfoliated graphene oxide powder with controlled lateral dimensions and thickness and a predetermined defect ratio was prepared and dispersed in ultrapure water to form a graphene oxide dispersion with a specific structure. Deionized water and anhydrous ethanol were mixed, and phytic acid and trifluoroacetic acid were added to adjust the polarity and pH value, thus preparing a composite acidic alcohol-water medium. Fluorinated polyether silane coupling agent is pumped into a composite acidic alcohol-water medium at a constant rate and mixed with a graphene oxide dispersion with a specific structure. The covalent grafting reaction is stimulated under an asymmetric dual-frequency pulsed ultrasonic field and stepped temperature control to form a fluorosilane-modified graphene oxide slurry. The fluorosilane-modified graphene oxide slurry was subjected to centrifugal washing and freeze-drying to remove the solvent, resulting in fluorosilane-modified graphene oxide nanosheets with a surface rich in fluorinated alkyl groups and active silanol groups.

3. The method for preparing a weather-resistant railway turnout coating according to claim 1, characterized in that, The process involves a stepwise temperature-increasing polymerization of aliphatic diisocyanate, polytetrafluoroethylene glycol, and polycarbonate glycol under inert gas protection and in the presence of a catalyst to synthesize a weather-resistant polyurethane prepolymer with fluorinated main-chain blocks and isocyanate end groups, comprising: The selected polycarbonate diol and polytetrafluoroethylene diol were subjected to extreme dehydration treatment under constant temperature and vacuum conditions to obtain anhydrous macromolecular diol raw materials with a moisture content lower than a preset threshold. Adding trace amounts of non-toxic organic bismuth-zinc complex isooctanoate to aliphatic diisocyanate mixed monomers forms a highly efficient synergistic catalytic isocyanate system. Under the protection of high-purity nitrogen, the highly efficient synergistic catalytic isocyanate system is mixed with polytetrafluoroethylene glycol in anhydrous macromolecular diol raw material and reacted at a first set temperature to generate fluorine-rich micro-region preblocks. Polycarbonate diol from anhydrous macromolecular diol raw material was added dropwise at a uniform rate to a fluorine-rich micro-region preblock, and in-situ block copolymerization was carried out by smooth heating. The prepolymer was then cooled and vacuum-cured to synthesize a weather-resistant polyurethane prepolymer with fluorine-containing main chain blocks and isocyanate-terminated end groups.

4. The method for preparing a weather-resistant railway turnout coating according to claim 1, characterized in that, The process involves adding fluorosilane-modified graphene oxide nanosheets to the weather-resistant polyurethane prepolymer at a predetermined mass fraction, followed by multi-stage gradient temperature-controlled mixing using a vacuum high-shear emulsifier. This allows the nanosheets to form an isotropic three-dimensional network dispersion structure within the prepolymer matrix, resulting in a homogeneous nanocomposite prepolymer phase, comprising: A low-boiling-point, non-active, environmentally friendly diluent was sprayed onto fluorosilane-modified graphene oxide nanosheets and then subjected to low-speed planetary stirring under vacuum to allow the fluoroalkyl groups on the surface to spread, resulting in an interface-preactivated nanosheet slurry. The interface pre-activated nanosheet slurry is rapidly pumped into the main emulsification kettle containing the weather-resistant polyurethane prepolymer at a set temperature. Under extreme vacuum, the first stage of high-speed high-frequency crushing and mixing is performed to force the tearing of the aggregates, forming a submicron-level forced dispersion initial mixed phase. The submicron-level forced dispersion initial mixed phase is subjected to a second stage of medium-speed homogenization and temperature-controlled mixing to induce trace interfacial grafting between surface-active silanol groups and terminal isocyanate groups, forming an interfacial anchored semi-homogeneous phase. A third-stage low-speed curing and cooling mixing process was performed on the interface-anchored semi-homogeneous phase to promote the self-assembly and relaxation of polymer chain segments to construct a three-dimensional network dispersion structure, thereby obtaining a nanocomposite prepolymer homogeneous phase with thixotropic properties.

5. The method for preparing a weather-resistant railway turnout coating according to claim 1, characterized in that, The hindered amine light stabilizer presolvent and the terminal amino hyperbranched polymer crosslinking agent are sequentially added dropwise to the homogeneous phase of the nanocomposite prepolymer. Under constant temperature water bath and mechanical stirring conditions, a mild pre-crosslinking reaction is induced between the terminal amino groups and the isocyanate groups in the prepolymer to prepare a highly active weather-resistant coating stock solution with self-leveling properties, comprising: Etherified hindered amine light stabilizers were completely dissolved in a mixture of polar and nonpolar solvents and degassed by ultrasonication in the dark to obtain molecularly deassociated hindered amine light stabilizer presolvents. Under a constant mechanical stirring shear field, the hindered amine light stabilizer presolvent is added dropwise to the isothermal homogeneous phase of the nanocomposite prepolymer, and is locked in the interchain gap by hydrogen bonding and conjugation to form a light stabilizer embedded homogeneous phase. Spherical terminal amino hyperbranched polymer crosslinking agent was atomized and sprayed into a homogeneous phase embedded with a light stabilizer to induce a rapid nucleophilic addition reaction between the terminal amino groups and isocyanate groups, thus constructing a microscopic star-shaped-linear pre-interpenetrating network prototype. The apparent viscosity of the microscopic star-shaped-linear pre-interpenetrating network prototype is monitored online. When the viscosity smoothly rises to the preset target range, the water bath temperature is immediately reduced and the stirring speed is slowed down to freeze the crosslinking reaction, thus obtaining a highly active weather-resistant coating stock solution with self-leveling properties.

6. The method for preparing a weather-resistant railway turnout coating according to claim 1, characterized in that, The process involves uniformly coating a highly active weather-resistant coating solution onto the surface of a railway turnout metal substrate that has undergone surface sandblasting and roughening treatment, followed by a pre-programmed step-induced thermo-crosslinking curing process. This process promotes the formation of an interpenetrating network structure of fluorosilicone-modified nanophase and polymeric organic phase within the coating system, resulting in in-situ curing of the weather-resistant railway turnout coating on the metal substrate surface. The process includes: High-pressure airflow mixed with brown corundum abrasive is used to perform multi-angle sandblasting roughening of railway turnout metal substrates, remove the passivation layer and expose free metal hydroxyl groups, and obtain highly active metal substrates with specific micro-roughness. The highly active weather-resistant coating stock solution is uniformly sprayed onto the surface of the highly active metal substrate, and the preset wet film thickness is controlled to form a highly active wet film coating. The highly active wet film coating is placed in a low-humidity infrared environment to perform the first stage of mild thermal curing, driving the fluorine-containing components to migrate to the surface and self-assemble on the polar surface to form a superhydrophobic fluorine-containing armor layer. The coating system with a superhydrophobic fluorine-containing armor layer is subjected to a second stage of gradual temperature rise curing to awaken the residual amino groups of the hyperbranched crosslinking agent to carry out deep crosslinking in order to build a dense polymer skeleton and form a deep crosslinking transition coating. The deep cross-linked transition coating is subjected to a third stage of high-temperature baking and locking, which forces the inorganic nanophase domain and the pure organic phase domain to become extremely entangled. Finally, the stress is released by slow cooling, and the weather-resistant railway turnout coating is formed in situ on the surface of the metal substrate.

7. A weather-resistant railway turnout coating, characterized in that, After the coating is cured into a film, it has an isotropic three-dimensional network dispersed microstructure and a gradient phase separation configuration in the thickness direction.

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