High-weather-resistance multifunctional rail transit polymer coating, preparation method and application thereof

Abstract

The application relates to a high-weather-resistance multifunctional rail transit polymer coating as well as a preparation method and application thereof, and relates to the technical field of rail transit coatings. The high-weather-resistance multifunctional rail transit polymer coating comprises an A component and a B component; the A component comprises the following substances in a mass fraction: 25-35% of silicone-modified acrylic resin; 5-10% of nano-silicon dioxide loaded polyacrylic resin; 4-8% of functionalized nano-aluminum oxide-nano-cerium oxide composite material; 25-35% of titanium white powder; 0.5-1.0% of a dispersing agent; and 20-30% of a solvent; the B component comprises the following substances in a mass fraction: 70-80% of isocyanate resin; and 20-30% of a solvent. The high-weather-resistance multifunctional rail transit polymer coating has excellent weather resistance, wear resistance, acid and alkali resistance, anti-yellowing property, water and oil resistance, high gloss, stain resistance and other multifunctional properties through the synergistic effect of the components.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a high weather-resistant, multifunctional polymer coating for rail transit, its preparation method, and its application. Background Technology

[0002] Currently, the topcoat system for rail transit coatings mainly uses acrylic polyurethane system, which has advantages such as good workability, good adhesion, good fullness, high gloss, and good weather resistance.

[0003] Rail transit coatings, especially those used on high-speed trains, have even stricter requirements for decorative and protective functions. High-speed trains travel at high speeds, resulting in greater impact from airborne debris on their exterior surfaces, leading to more severe wear and tear, damage to the paint coating, and a decline in both decorative and protective properties. Furthermore, high-speed trains have stringent operational and maintenance requirements. First-level maintenance is generally mandated after 4000-5000 kilometers or 48 hours of operation, though this can be extended to 72 hours. This involves a comprehensive inspection of the running gear, brakes, and pantograph, as well as confirming the proper functioning of the superstructure and performing thorough cleaning both inside and outside the train. Frequent cleaning accelerates physical damage to the paint film, causing stains to penetrate and become difficult to remove. Therefore, regular deep cleaning with strong acidic or alkaline detergents is necessary. However, these acidic or alkaline media further accelerate chemical damage to the paint film, often resulting in premature yellowing, loss of gloss, contamination, and even blistering. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a high weather-resistant multifunctional polymer coating for rail transit, its preparation method and application. The coating film formed when used in the rail transit field (e.g., on the outer surface of a high-speed train) has excellent wear resistance, acid and alkali resistance, yellowing resistance, high gloss, easy cleaning and other multifunctional properties.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high weather-resistant, multifunctional polymer coating for rail transit, comprising component A and component B;

[0007] Component A comprises the following substances by mass fraction:

[0008]

[0009]

[0010] Component B comprises the following substances by mass fraction:

[0011] Isocyanate resin 70-80%;

[0012] Solvent content: 20-30%.

[0013] The high weather-resistant multifunctional rail transit polymer coating of this invention achieves its multifunctionality by adding the organosilicon-modified acrylic resin, the nano-silica-supported polyacrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, and the titanium dioxide to component A, and the isocyanate resin in component B.

[0014] The high weather-resistant, multifunctional polymer coating for rail transit of this invention incorporates 25-35 wt% of silicone-modified acrylic resin and 5-10 wt% of nano-silica-supported polyacrylic resin in component A. These components participate in the network crosslinking process during coating curing, improving the weather resistance and stain resistance of the coating surface. The silicone-modified acrylic resin contains a large number of active groups and exhibits high reactivity, participating in the network crosslinking process during coating curing and enhancing the weather resistance and stain resistance of the coating surface. The nano-silica-supported polyacrylic resin contains multiple hydroxyl groups and exhibits high reactivity, enabling it to participate in the network crosslinking process during coating curing, further synergistically improving the weather resistance and stain resistance of the coating surface with the silicone-modified acrylic resin. Furthermore, the nano-silica-supported polyacrylic resin, by loading nano-silica onto the polyacrylic resin in a supported form, inhibits the penetration of small oil molecules caused by the lipophilic groups in the polyacrylic resin or coating through the effect of nano-silica on these molecules. This invention has discovered that using nano-silica to support polyacrylic acid resin, due to the unique three-dimensional structure of nano-silica, with its high porosity and large specific surface area, can effectively inhibit the penetration of small oil molecules in the coating film. It is important to emphasize that this invention combines inorganic nanoparticles and polyacrylic acid resin in a supported form, forming inorganic nanoparticle-supported polyacrylic acid resin, which significantly improves the oil resistance of the coating film. Simply adding nano-silica to component A in a conventional form (non-supported form) will not achieve the goal of inhibiting the penetration of small oil molecules into the coating film. Therefore, the high weather-resistant multifunctional rail transit polymer coating of this invention, by supporting polyacrylic acid resin with nano-silica in component A, utilizes the multiple hydroxyl groups in its structure to participate in curing and cross-linking, thereby increasing the cross-linking density and improving the weather resistance and stain resistance of the coating film; on the other hand, it utilizes the supported nano-silica to achieve the purpose of inhibiting the penetration of oil molecules into the coating film.

[0015] The high weather-resistant multifunctional rail transit polymer coating of the present invention further includes 4-8 wt% of functionalized nano-alumina-nano-cerium oxide composite material in component A; the functionalized nano-alumina-nano-cerium oxide composite material has one or more functional groups among hydroxyl, carboxyl, amino or epoxy groups, which makes the functionalized nano-alumina-nano-cerium oxide composite material have good compatibility, dispersibility and reactivity in the coating. The functionalized nano-alumina-nano-cerium oxide composite material exhibits good bonding strength and compatibility with the silicone-modified acrylic resin and / or the nano-silica-supported polyacrylic resin. Simultaneously, the functionalized nano-alumina-nano-cerium oxide composite material can crosslink with both the silicone-modified acrylic resin and / or the nano-silica-supported polyacrylic resin, as well as with the isocyanate resin. This results in a complex crosslinking network formed among the silicone-modified acrylic resin, the nano-silica-supported polyacrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, and the isocyanate resin, significantly improving the wear resistance and scratch resistance of the coating film. Furthermore, the coating film does not peel off after solvent washing and exhibits good water resistance, acid resistance, and alkali resistance. Additionally, the functionalized nano-alumina-nano-cerium oxide composite material utilizes the antioxidant properties of nano-alumina and nano-cerium oxide to provide the coating with a certain antioxidant effect, preventing premature yellowing of the coating film.

[0016] The high weather-resistant, multifunctional rail transit polymer coating of this invention also includes 25-35% titanium dioxide in component A; the addition of titanium dioxide can improve the gloss and mechanical properties of the coating film. Furthermore, since the amount of the added functionalized nano-alumina-nano-cerium oxide composite material is relatively small, it does not affect the color of the coating. Together with the 25-35 wt% titanium dioxide, they jointly improve the mechanical properties of the coating film.

[0017] The high weather-resistant multifunctional rail transit polymer coating of the present invention achieves excellent weather resistance, abrasion resistance, acid and alkali resistance, anti-yellowing, water and oil resistance, high gloss, and stain resistance in the coating film formed by the high weather-resistant multifunctional rail transit polymer coating through the synergistic effect of component A and component B, especially through the synergistic effect of the organosilicon modified acrylic resin, the nano-silica supported polyacrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, and the isocyanate resin.

[0018] Furthermore, the preparation method of the nano-silica-supported polyacrylic acid resin includes the following steps:

[0019] (1) Preparation of acryloyl chloride modified nano-silica carrier:

[0020] Nano-silica was mixed and dispersed with ethanol and n-heptane. Acryloyl chloride was added at 0°C, the mixture was heated to room temperature, and the reaction was carried out for 24 hours. The mixture was filtered, and the solid was washed with n-heptane and dried to obtain acryloyl chloride modified nano-silica carrier.

[0021] (2) Preparation of nano-silica supported α-diimine palladium catalyst:

[0022] α-Diimide palladium was reacted with a cationizing agent in anhydrous diethyl ether for 10-20 minutes, then the acryloyl chloride-modified nano-silica support was added, and the reaction was carried out for 24 hours. Then, n-heptane was added, the mixture was filtered, washed, and dried under vacuum to obtain a nano-silica-supported α-diimide palladium catalyst. The loading of the α-diimide palladium catalyst in the inorganic nanoparticles was 1-4 wt%.

[0023] (3) Preparation of nano-silica-supported polyacrylic acid resin:

[0024] Under the action of the nano-silica-supported α-diimide palladium catalyst, propylene and acrylate monomers with silane-protected hydroxyl groups are copolymerized. The pressure is set at 0.1-5 atm. After precipitation with ethanol, the product is a colorless and transparent oil. Then, the colorless and transparent oil is treated with tetra-n-butylammonium fluoride solution to remove the protection of hydroxyl groups, thereby obtaining nano-silica-supported polyacrylic acid resin containing multiple hydroxyl groups.

[0025] The nano-silica-supported polyacrylic acid resin obtained by the above preparation method has multiple hydroxyl groups and high reactivity. At the same time, the polyacrylic acid resin is supported on the nano-silica, which helps to inhibit the penetration of small oil molecules into the coating film.

[0026] Furthermore, in the nano-silica-supported polyacrylic resin, the loading amount of the polyacrylic resin in the nano-silica is 30-50 wt%, and the number average molecular weight of the polyacrylic resin is between 10,000 and 20,000.

[0027] Furthermore, the preparation method of the functionalized nano-alumina-nano-cerium oxide composite material includes the following steps:

[0028] (a) Preparation of functionalized nano-alumina and functionalized nano-cerium oxide:

[0029] Functionalized nano-alumina was obtained by modifying nano-alumina with a silane coupling agent.

[0030] Functionalized cerium oxide nanoparticles were obtained by modifying cerium oxide nanoparticles with silane coupling agents.

[0031] (b) Preparation of functionalized nano-alumina-nano-cerium oxide composite materials:

[0032] Functionalized nano-cerium oxide and functionalized nano-alumina are mixed and calcined to obtain the functionalized nano-alumina-nano-cerium oxide composite material.

[0033] This invention utilizes silane coupling agents to modify nano-alumina and nano-cerium oxide, respectively, to obtain functionalized nano-alumina and functionalized nano-cerium oxide. These functionalized nano-alumina and functionalized nano-cerium oxide possess functional groups (one or more of hydroxyl, carboxyl, amino, or epoxy groups). The resulting composite material is obtained through mixed calcination. This composite material exhibits strong reactivity and excellent crosslinking properties, contributing to improved wear resistance and scratch resistance of the coating.

[0034] Furthermore, in the functionalized nano-alumina-nano-cerium oxide composite material, the mass ratio of the functionalized nano-alumina to the functionalized nano-cerium oxide is 1.0-1.5:1. By limiting the mixing and calcination of the functionalized nano-alumina and functionalized nano-cerium oxide in the above-mentioned mass ratio, the functionalized nano-cerium oxide in the functionalized nano-alumina-nano-cerium oxide composite material can be distributed on the surface of the functionalized nano-alumina without completely covering it. This allows the functional groups of both the functionalized nano-cerium oxide and the functionalized nano-alumina to crosslink with the organosilicon-modified acrylic resin, and / or the nano-silica-supported polyacrylic acid resin, and / or the isocyanate resin, respectively, thereby increasing the crosslinking density.

[0035] Furthermore, the silane coupling agent used in the preparation of functionalized nano-alumina and functionalized nano-cerium oxide is one or more selected from 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-(triethoxysilyl)propylsuccinic anhydride, or N-β-(aminoethyl)-γ-aminopropylmethyl-dimethoxysilane. The silane coupling agents listed above are not intended to limit the invention, and those skilled in the art can select other silane coupling agents according to actual needs.

[0036] Furthermore, the high weather-resistant multifunctional rail transit polymer coating also includes defoamers, film-forming aids, leveling agents, and other additives. The high weather-resistant multifunctional rail transit polymer coating of the present invention can also incorporate defoamers, film-forming aids, leveling agents, and other related additives to improve its performance; this is a conventional technique in the field and will not be elaborated upon here.

[0037] Furthermore, the isocyanate resin is Covestro Desmodur N3300, Desmodur N3790 BA, Asahi Kasei Durnate TPA 100, THA-100, or Wanhua. At least one of the following. The isocyanate resins listed above are not intended to limit the invention, and those skilled in the art can select other isocyanate resins according to actual needs.

[0038] Furthermore, the mass ratio of component A to component B is 4-6:1.

[0039] This invention also provides a method for preparing any of the above-mentioned high weather-resistant multifunctional rail transit polymer coatings, comprising the following steps:

[0040] Preparation of Component A: In a container, add the organosilicon-modified acrylic resin, the nano-silica-modified acrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, the titanium dioxide, the dispersant, and a portion of the solvent according to the proportion of Component A. Disperse at high speed for 30 minutes and grind to a fineness ≤10μm before discharging. Then add the remaining substances and disperse at high speed for 30 minutes. Filter the mixture using a 300-mesh filter bag to obtain Component A.

[0041] Preparation of component B: Add each component to a container according to the proportion of component B and mix evenly to obtain component B;

[0042] Component A and component B are mixed to obtain the high weather-resistant multifunctional rail transit polymer coating.

[0043] The present invention also provides an application of any of the above-described high weather-resistant multifunctional rail transit polymer coatings in forming a paint film on the surface of a rail transit EMU shell.

[0044] The high weather-resistant multifunctional rail transit polymer coating described above is sprayed onto the shell surface of the EMU in the field of rail transit, and after curing, a high weather-resistant multifunctional rail transit polymer coating film is formed on the shell surface of the EMU.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The high weather-resistant multifunctional rail transit polymer coating of this invention achieves excellent weather resistance, wear resistance, acid and alkali resistance, anti-yellowing, high gloss, high hardness, and stain resistance in the coating film through the synergistic effect of components A and B, especially through the synergistic effect of the organosilicon-modified acrylic resin, the nano-silica-supported polyacrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, and the isocyanate resin. In particular, it has long-lasting anti-oil stain performance. Detailed Implementation

[0047] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0048] The organosilicon-modified hydroxyl acrylic resin used in this embodiment of the invention is organosilicon-modified hydroxyl acrylic resin WE-D9540 produced by Anhui Xinno Chemical Co., Ltd., with a solid content of 50% ± 3% and a solid content of hydroxyl functional groups of 3.9%.

[0049] The silica-supported polyacrylic acid resin used in this embodiment of the invention is prepared through the following steps:

[0050] (1) Preparation of acryloyl chloride modified nano-silica carrier:

[0051] Nano-silica was mixed and dispersed with ethanol and n-heptane. Acryloyl chloride was added at 0°C, the mixture was heated to room temperature, and the reaction was carried out for 24 hours. The mixture was filtered, and the solid was washed with n-heptane and dried to obtain acryloyl chloride modified nano-silica carrier.

[0052] (2) Preparation of nano-silica supported α-diimine palladium catalyst:

[0053] α-Diimide palladium and the cationizing agent NaBAF were added to anhydrous diethyl ether and reacted for 10-20 minutes. The acryloyl chloride-modified nano-silica support was added and reacted for 24 hours. Then, n-heptane was added, filtered, washed, and dried under vacuum. The α-diimide palladium catalyst was linked to nano-silica through chemical bonds to obtain a nano-silica-supported α-diimide palladium catalyst.

[0054] (3) Preparation of nano-silica-supported polyacrylic acid resin:

[0055] Under the action of the nano-silica-supported α-diimine palladium catalyst, propylene and acrylate monomers with silane-protected hydroxyl groups are copolymerized. The pressure is set at 0.1-5 atm. After precipitation with ethanol, the product is a colorless and transparent oil. Then, the colorless and transparent oil is treated with tetra-n-butylammonium fluoride solution to remove the protection of hydroxyl groups, thereby obtaining nano-silica-supported polyacrylic acid resin containing multiple hydroxyl groups. The loading amount of polyacrylic acid resin in nano-silica is 50 wt%.

[0056] The preparation method of the functionalized nano-alumina-nano-cerium oxide composite material used in this embodiment of the invention includes the following steps:

[0057] (a) Preparation of functionalized nano-alumina and functionalized nano-cerium oxide:

[0058] (a1) Preparation of functionalized nano-alumina:

[0059] According to the weight percentage, 10 parts of nano-alumina and 40 parts of silane coupling agent 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane were dispersed in 400 parts of water and stirred to carry out the reaction at a temperature of 65°C for 2 hours. After stirring, the mixture was filtered, washed and dried to obtain functionalized nano-alumina.

[0060] (a2) Preparation of functionalized nano-cerium oxide: 10 parts of nano-cerium oxide and 50 parts of silane coupling agent N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane were dispersed in 500 parts of water and stirred for 40 min. After stirring, the mixture was filtered, washed and dried to obtain functionalized cerium oxide.

[0061] (b) Preparation of functionalized nano-alumina-nano-cerium oxide composite material: Take 5 parts of functionalized cerium oxide and 6 parts of functionalized nano-alumina and disperse them in 100 parts of water, stir for 2 hours, filter, wash and dry after stirring, and keep warm at 450℃ for 5 hours to obtain nano-alumina-cerium oxide composite material.

[0062] The titanium dioxide used in this embodiment of the invention is of type R-706.

[0063] The isocyanate resin used in the embodiments of the present invention is Covestro Desmodur N3300.

[0064] Example 1

[0065] This embodiment provides a high weather-resistant, multifunctional polymer coating for rail transit, comprising component A and component B;

[0066] Component A includes the following substances by mass fraction:

[0067]

[0068] Component B comprises the following substances by mass fraction:

[0069] 70% isocyanate resin;

[0070] Solvent 30%.

[0071] The weight ratio of component A to component B is 4:1.

[0072] The preparation method of the high weather-resistant multifunctional rail transit polymer coating in this embodiment includes the following steps:

[0073] (1) Preparation of component A: In a container, add organosilicon-modified acrylic resin, nano-silica-modified acrylic resin, functionalized nano-alumina-nano-cerium oxide composite material, titanium dioxide, dispersant, and part (15wt%) of solvent according to the ratio of component A. Disperse at high speed for 30 min and grind to fineness ≤10μm before discharge. Then add defoamer, film-forming aid, leveling agent, and the remaining solvent. Disperse at high speed for 30 min. Filter the material using a 300-mesh filter bag to obtain component A.

[0074] (2) Preparation of component B: Add each component to a container according to the proportion of component B and mix evenly to obtain component B;

[0075] (3) Mix component A and component B according to the ratio to obtain the high weather resistance multifunctional rail transit polymer coating of this embodiment.

[0076] Example 2

[0077] This embodiment provides a high weather-resistant, multifunctional polymer coating for rail transit, comprising component A and component B;

[0078] Component A includes the following substances by mass fraction:

[0079]

[0080]

[0081] Component B comprises the following substances by mass fraction:

[0082] Isocyanate resin 80%;

[0083] Solvent 20%.

[0084] The weight ratio of component A to component B is 5:1.

[0085] The preparation method of the high weather-resistant multifunctional rail transit polymer coating in this embodiment is the same as that in Example 1.

[0086] Example 3

[0087] This embodiment provides a high weather-resistant, multifunctional polymer coating for rail transit, comprising component A and component B;

[0088] Component A includes the following substances by mass fraction:

[0089]

[0090] Component B comprises the following substances by mass fraction:

[0091] 70% isocyanate resin;

[0092] Solvent 30%.

[0093] The weight ratio of component A to component B is 6:1.

[0094] The preparation method of the high weather-resistant multifunctional rail transit polymer coating in this embodiment is the same as that in Example 1.

[0095] Example 4

[0096] This embodiment provides a high weather-resistant, multifunctional polymer coating for rail transit, comprising component A and component B;

[0097] Component A includes the following substances by mass fraction:

[0098]

[0099] Component B comprises the following substances by mass fraction:

[0100] Isocyanate resin 80%;

[0101] Solvent 20%.

[0102] The weight ratio of component A to component B is 5:1.

[0103] The preparation method of the high weather-resistant multifunctional rail transit polymer coating in this embodiment is the same as that in Example 1.

[0104] Comparative Example 1

[0105] This comparative example provides a polymer coating, comprising component A and component B;

[0106] Component A includes the following substances by mass fraction:

[0107]

[0108] Component B comprises the following substances by mass fraction:

[0109] Isocyanate resin 80%;

[0110] Solvent 20%.

[0111] The weight ratio of component A to component B is 5:1.

[0112] The preparation method of the high weather-resistant multifunctional rail transit polymer coating of this comparative example includes the following steps:

[0113] (1) Preparation of component A: In a container, add organosilicon-modified acrylic resin, nano silica, nano cerium oxide, titanium dioxide, nano alumina, dispersant, and part (15wt%) of solvent according to the ratio of component A. Disperse at high speed for 30 min and grind to fineness ≤10μm before discharge. Then add defoamer, film-forming aid, leveling agent, and the remaining solvent. Disperse at high speed for 30 min. Filter the material using a 300-mesh filter bag to obtain component A.

[0114] (2) Preparation of component B: Add each component to a container according to the proportion of component B and mix evenly to obtain component B;

[0115] (3) Mix component A and component B according to the ratio to obtain the high weather resistance multifunctional rail transit polymer coating of this embodiment.

[0116] Example 5

[0117] This embodiment provides an application of a high weather-resistant, multifunctional polymer coating for rail transit in forming a paint film on the surface of a rail transit EMU (Electric Multiple Unit) shell.

[0118] The high weather-resistant multifunctional rail transit polymer coatings of Examples 1-4 were sprayed onto the shell surface of the EMU in the field of rail transit. After curing, a high weather-resistant multifunctional rail transit polymer coating film was formed on the shell surface of the EMU.

[0119] Performance testing

[0120] The performance of the high weather-resistant multifunctional rail transit polymer coatings of Examples 1-4 and the polymer coating of Comparative Example 1 were tested respectively. The test results are shown in Table 1.

[0121] Table 1 Performance Test Results

[0122]

[0123]

[0124] As can be seen from Table 1, the high weather-resistant multifunctional rail transit polymer coatings of Examples 1-4 of the present invention, through the synergistic effect of components A and B, especially through the synergistic effect of the organosilicon-modified acrylic resin, the nano-silica-supported polyacrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, and the isocyanate resin, achieve excellent weather resistance, wear resistance, acid and alkali resistance, anti-yellowing, water and oil resistance, high gloss, stain resistance and other multifunctional properties of the coating film formed by the high weather-resistant multifunctional rail transit polymer coatings, making them suitable for the shell surface of EMU trains in the rail transit field.

[0125] The coating of Comparative Example 1 did not use the nano-silica-supported polyacrylic resin and functionalized nano-alumina-nano-cerium oxide composite material of the present invention. Instead, nano-silica and nano-cerium oxide were added to component A of the coating. Its coating performance was relatively poor and could not meet the multi-functional requirements of the shell surface coating of EMU in the field of rail transit.

[0126] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A high weather-resistant, multifunctional polymer coating for rail transit, characterized in that: Includes component A and component B; Component A comprises the following substances by mass fraction: Component B comprises the following substances by mass fraction: In the nano-silica-supported polyacrylic acid resin, the loading amount of polyacrylic acid resin in the nano-silica is 30-50 wt%; the preparation method of the nano-silica-supported polyacrylic acid resin... Includes the following steps: (1) Preparation of acryloyl chloride modified nano silica carrier: Nano-silica was mixed and dispersed with ethanol and n-heptane. Acryloyl chloride was added at 0°C, the mixture was heated to room temperature, and the reaction was carried out for 24 hours. The mixture was filtered, and the solid was washed with n-heptane and dried to obtain acryloyl chloride modified nano-silica carrier. (2) Preparation of nano-silica supported α-diimine palladium catalyst: α-Diimide palladium was reacted with a cationizing agent in anhydrous diethyl ether for 10-20 minutes, followed by the addition of the acryloyl chloride-modified nano-silica support. The reaction was continued for 24 hours, then n-heptane was added. The mixture was filtered, washed, and dried under vacuum to obtain a nano-silica-supported α-diimide palladium catalyst. The loading of the α-diimide palladium catalyst in the inorganic nanoparticles was 1-4 wt%. (3) Preparation of nano-silica-supported polyacrylic acid resin: Under the action of the nano-silica-supported α-diimide palladium catalyst, propylene and acrylate monomers with silane-protected hydroxyl groups are copolymerized. The pressure is set at 0.1-5 atm. After precipitation with ethanol, the product is a colorless and transparent oil. Then, the colorless and transparent oil is treated with tetra-n-butylammonium fluoride solution to remove the protection of hydroxyl groups, thereby obtaining nano-silica-supported polyacrylic acid resin containing multiple hydroxyl groups. The preparation method of the functionalized nano-alumina-nano-cerium oxide composite material includes the following steps: (a) Preparation of functionalized nano-alumina and functionalized nano-cerium oxide: Functionalized nano-alumina was obtained by modifying nano-alumina with a silane coupling agent. Functionalized cerium oxide nanoparticles were obtained by modifying cerium oxide nanoparticles with silane coupling agents. (b) Preparation of functionalized nano-alumina-nano-cerium oxide composite materials: Functionalized nano-cerium oxide and functionalized nano-alumina are mixed and calcined to obtain the functionalized nano-alumina-nano-cerium oxide composite material.

2. The high weather-resistant multifunctional rail transit polymer coating according to claim 1, characterized in that: The silane coupling agent is at least one of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-(triethoxysilyl)propylsuccinic anhydride, or N-β(aminoethyl)-γ-aminopropylmethyl-dimethoxysilane.

3. The high weather-resistant multifunctional rail transit polymer coating according to claim 1, characterized in that: Component A also includes defoamers, film-forming aids, and leveling agents.

4. The high weather-resistant multifunctional rail transit polymer coating according to claim 1, characterized in that: The isocyanate resin is at least one of Covestro Desmodur N3300, Desmodur N3790 BA, Asahi Kasei Durnate TPA 100, THA-100, and Wanhua WANNATE® HB-100.

5. The high weather-resistant multifunctional rail transit polymer coating according to claim 1, characterized in that: The mass ratio of component A to component B is 4-6:

1.

6. A method for preparing a high weather-resistant, multifunctional polymer coating for rail transit according to any one of claims 1-5, characterized in that: Includes the following steps: Preparation of Component A: In a container, add the organosilicon-modified acrylic resin, the nano-silica-modified acrylic resin, the functionalized nano-alumina-nano-cerium oxide composite material, the titanium dioxide, the dispersant, and a portion of the solvent according to the proportion of Component A. Disperse at high speed for 30 minutes and grind to a fineness ≤10μm before discharging. Then add the remaining substances and disperse at high speed for 30 minutes. Filter the mixture using a 300-mesh filter bag to obtain Component A. Preparation of component B: Add each component to a container according to the proportion of component B and mix evenly to obtain component B; Component A and component B are mixed to obtain the high weather-resistant multifunctional rail transit polymer coating.

7. The application of the high weather-resistant multifunctional rail transit polymer coating as described in any one of claims 1-5 to form a paint film on the surface of a rail transit EMU shell.

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