Protective coating as well as preparation method and application thereof

Abstract

The invention belongs to the field of coatings, and particularly discloses a protective coating and a preparation method and application thereof.The protective coating is prepared from, by mass, 60-100 parts of silane-terminated polyether, 40-70 parts of hydrophobic modified diluent, 50-90 parts of flame-retardant plasticizer, 180-240 parts of flame-retardant filler, 10-20 parts of pigment, 0.5-5 parts of ultraviolet light absorber, 0.5-5 parts of light stabilizer and 1-10 parts of thixotropic agent. 1-10 parts of a silane dewatering agent, 1-10 parts of a silane coupling agent and 0.1-3 parts of a catalyst. The flame-retardant plasticizer and the inorganic flame-retardant filler are compounded, and the hydrophobic modified diluent is combined, so that a coating formed by the protective paint has excellent elasticity, flame retardance, salt mist resistance, acid and alkali resistance, stone impact resistance, moisture resistance and the like, the flame-retardant grade of the coating reaches FV-0 grade, and the coating can meet the flame-retardant requirement on a new energy automobile battery chassis; and the development of an automobile chassis armor technology is promoted.

Description

Technical Field

[0001] The invention belongs to the field of coatings, and in particular relates to a protective coating and a preparation method and application thereof. Background Art

[0002] With the continuous development of the automobile industry, consumers have higher and higher requirements for automobile performance, durability and safety. As an important structural part of the vehicle, the automobile chassis often faces challenges such as harsh road conditions, water vapor erosion, and stone impact. Therefore, it is particularly important to protect the chassis from damage. As an effective means of protection, chassis armor enhances the wear resistance, corrosion resistance and sound insulation of the chassis by coating special materials on the chassis.

[0003] The chassis protection materials currently on the market (for example: oily chassis anti-rust glue or water-soluble chassis anti-rust glue) have certain limitations, such as poor environmental protection, weak adhesion, poor sound-absorbing effect, etc., and do not meet the flame retardant requirements of the emerging new energy vehicle battery chassis. For example: oily (solvent-based) chassis anti-rust glue contains toxic substances that are harmful to the human body, which has a negative impact on the environment and human health, and their adhesive layer is hard and lacks elasticity, and the effect of chassis sound insulation is poor. Water-soluble chassis anti-rust glue uses water as a diluent, does not contain toxic substances, and meets environmental protection requirements, but its water resistance and mechanical strength are not ideal, and the construction and curing time is long. These problems have greatly restricted the development and application of chassis protection materials. Summary of the invention

[0004] In order to overcome at least one technical problem existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a protective coating.

[0005] A second object of the present invention is to provide a method for preparing a protective coating.

[0006] A third object of the present invention is to provide a vehicle.

[0007] A fourth object of the present invention is to provide application of the above-mentioned protective coating in the field of transportation vehicles.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a protective coating, comprising the following components in parts by weight: 60-100 parts of silane-terminated polyether, 40-70 parts of hydrophobically modified diluent, 50-90 parts of flame retardant plasticizer, 180-240 parts of flame retardant filler, 10-20 parts of pigment, 0.5-5 parts of ultraviolet absorber, 0.5-5 parts of light stabilizer, 1-10 parts of thixotropic agent, 1-10 parts of silane dehydrating agent, 1-10 parts of silane coupling agent, and 0.1-3 parts of catalyst.

[0010] In the protective coating, the amount of the silane-terminated polyether can be selected from 60 parts by mass, 65 parts by mass, 70 parts by mass, 75 parts by mass, 80 parts by mass, 85 parts by mass, 90 parts by mass, 95 parts by mass or 100 parts by mass.

[0011] In the protective coating, the amount of the hydrophobically modified diluent may be selected from 40 parts by mass, 45 parts by mass, 50 parts by mass, 55 parts by mass, 60 parts by mass, 65 parts by mass or 70 parts by mass.

[0012] In the protective coating, the amount of the flame retardant plasticizer can be selected from 50 parts by mass, 55 parts by mass, 60 parts by mass, 65 parts by mass, 70 parts by mass, 75 parts by mass, 80 parts by mass, 85 parts by mass or 90 parts by mass.

[0013] In the protective coating, the amount of the flame retardant filler can be selected from 180 parts by mass, 190 parts by mass, 200 parts by mass, 210 parts by mass, 220 parts by mass, 230 parts by mass or 240 parts by mass.

[0014] In the protective coating, the amount of the pigment can be selected from 10 parts by mass, 11 parts by mass, 12 parts by mass, 13 parts by mass, 14 parts by mass, 15 parts by mass, 16 parts by mass, 17 parts by mass, 18 parts by mass, 19 parts by mass or 20 parts by mass.

[0015] In the protective coating, the amount of the ultraviolet absorber can be selected from 0.5 parts by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass or 5 parts by mass.

[0016] In the protective coating, the amount of the light stabilizer can be selected from 0.5 parts by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass or 5 parts by mass.

[0017] In the protective coating, the amount of the thixotropic agent can be selected from 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass, 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, 9 parts by mass or 10 parts by mass.

[0018] In the protective coating, the amount of the silane dehydrating agent can be selected from 1 mass part, 2 mass parts, 3 mass parts, 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts, 8 mass parts, 9 mass parts or 10 mass parts.

[0019] In the protective coating, the amount of the silane coupling agent can be selected from 1 mass part, 2 mass parts, 3 mass parts, 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts, 8 mass parts, 9 mass parts or 10 mass parts.

[0020] In the protective coating, the amount of the catalyst can be selected from 0.1 parts by mass, 0.5 parts by mass, 1 part by mass, 2 parts by mass or 3 parts by mass.

[0021] Preferably, the silane-terminated polyether includes at least one of silyl-terminated polyether, dimethoxy-triethoxy mixed-terminated polyether, dimethoxy-terminated polyether, and triethoxy-terminated polyether.

[0022] Preferably, the hydrophobically modified diluent comprises the following raw materials in parts by weight: 15-40 parts of terminal hydroxyl polybutadiene, 5-20 parts of plasticizer, 1-10 parts of modifier, and 0.1-3 parts of end-capping agent; the modifier is isocyanate silane; and the end-capping agent is aminoalkyl silane.

[0023] Preferably, the plasticizer comprises a phthalate.

[0024] Preferably, the modifier includes at least one of isocyanate propyl methyl dimethoxy silane and isocyanate propyl triethoxy silane.

[0025] Preferably, the end-capping agent includes at least one of aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and γ-aminopropylmethyldiethoxysilane.

[0026] Preferably, the viscosity of the hydrophobically modified diluent measured at 25° C. is 0.3-3 Pa·s.

[0027] Preferably, the weight average molecular weight of the hydroxy-terminated polybutadiene is 1000-5000.

[0028] Preferably, the hydrophobically modified diluent is prepared by a preparation method comprising the following steps: mixing raw materials including terminal hydroxyl polybutadiene, a plasticizer and a modifier at 70-80° C., and then mixing with a capping agent at a temperature not exceeding 50° C. to obtain the hydrophobically modified diluent.

[0029] The protective coating of the present invention greatly improves the hydrophobic properties of the system by introducing a hydrophobic modified diluent, effectively reduces the erosion of the adhesive coating by rain, salt spray, acid, alkali, etc., enables the coating to be firmly attached to the surface of the automobile chassis, greatly improves the overall salt spray resistance, water resistance and acid and alkali resistance of the product, and effectively resists various external erosions. At the same time, the hydrophobic modified diluent is silane-terminated, participates in the curing reaction of the system, improves the bonding strength, and greatly improves the anti-stone impact performance of the coating.

[0030] Preferably, the flame retardant plasticizer includes a phosphate plasticizer; further preferably, the flame retardant plasticizer includes at least one of tricresyl phosphate, toluene diphenyl phosphate, tris-(chloroisopropyl) phosphate, and tris-(1,3-dichloroisopropyl) phosphate; even further preferably, the flame retardant plasticizer is selected from at least one of tricresyl phosphate and toluene diphenyl phosphate.

[0031] Preferably, the flame retardant filler includes at least one of antimony trioxide, aluminum hydroxide, magnesium hydroxide, hydrated zinc borate, ammonium polyphosphate, and melamine; further preferably, the flame retardant filler includes at least one of aluminum hydroxide and magnesium hydroxide.

[0032] Preferably, the pigment includes at least one of carbon black, titanium dioxide and iron oxide.

[0033] Preferably, the ultraviolet absorber includes at least one of a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a benzophenone ultraviolet absorber, a substituted acrylonitrile ultraviolet absorber, and a triazine ultraviolet absorber; further preferably, the ultraviolet absorber includes a benzotriazole ultraviolet absorber; still further preferably, the ultraviolet absorber includes at least one of UV-326, UV-327, UV-328, UV-329, and UV-5411; more preferably, the ultraviolet absorber includes at least one of UV-326, UV-328, and UV-329.

[0034] Preferably, the thixotropic agent includes at least one of polyamide wax, hydrogenated castor oil, fumed silica, and organic bentonite; further preferably, the thixotropic agent is polyamide wax, and polyamide wax Crayvallac SL can be selected.

[0035] Preferably, the light stabilizer includes a hindered amine light stabilizer; further preferably, the light stabilizer includes at least one of UV-292, UV-622, UV-770, UV-783, UV-791, and UV-944; even further preferably, the light stabilizer includes at least one of UV-292, UV-622, and UV-770.

[0036] Preferably, the silane dehydrating agent includes at least one of vinyltrimethoxysilane, vinyltriethoxysilane and vinyldimethoxysilane.

[0037] Preferably, the silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; further preferably, the silane coupling agent includes at least one of N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0038] Preferably, the catalyst comprises an organic tin catalyst; further preferably, the catalyst comprises at least one of dibutyltin dilaurate, dioctyltin dilaurate, dimethyltin dineodecanoate, dibutyltin diacetate, stannous octoate, and chelated tin; further preferably, the catalyst comprises a chelated tin catalyst, which can be selected from at least one of the chelated tin catalyst U-220H (dibutyltin bis(acetylacetonate)) and the chelated tin catalyst KRA-1.

[0039] The second aspect of the present invention provides a method for preparing the protective coating according to the first aspect of the present invention, comprising the following steps:

[0040] S1: heating and mixing raw materials including silane-terminated polyether, hydrophobically modified diluent, flame retardant plasticizer, flame retardant filler, pigment, ultraviolet absorber, light stabilizer and thixotropic agent to obtain a paste;

[0041] S2: mixing the paste with a silane dewatering agent, a silane coupling agent and a catalyst to obtain the protective coating.

[0042] Preferably, the temperature of the heating mixing reaction in step S1 is 100-120°C.

[0043] Preferably, step S1 is performed under a vacuum atmosphere; the vacuum degree is ≤-0.09 MPa.

[0044] Preferably, the time of the temperature-raising mixing reaction in step S1 is 2 to 4 hours.

[0045] Preferably, the mixing reaction temperature in step S2 does not exceed 50°C.

[0046] Preferably, the mixing reaction time in step S2 is 10 to 60 minutes.

[0047] The third aspect of the present invention provides an automobile, comprising a chassis, wherein a coating is provided on the surface of the chassis; the coating is formed by curing the protective coating described in the first aspect of the present invention.

[0048] The fourth aspect of the present invention provides the use of the protective coating described in the first aspect of the present invention in the field of transportation vehicles.

[0049] Preferably, the transportation vehicle is selected from a car, a train, a locomotive, a motorcycle or an airplane.

[0050] The beneficial effects of the present invention are as follows: the flame retardant plasticizer and the flame retardant filler are compounded to make the flame retardant grade of the protective coating reach FV-0, and the coating formed by the protective coating has excellent elasticity, flame retardant, salt spray resistance, acid and alkali resistance, stone impact resistance, moisture resistance, sound insulation and noise reduction and other properties by combining the hydrophobic modified diluent. Its flame retardant grade reaches FV-0, which can meet the flame retardant requirements on the battery chassis of new energy vehicles, ensure that the protective coating can be firmly attached to the chassis surface, and effectively resist various external erosions, and extend the service life of the vehicle chassis. In addition, the raw materials used in the protective coating of the present invention are non-toxic, green and environmentally friendly, and do not contain solvents. The formed coating has high bonding strength and excellent spray construction performance. No exclusive spray room is required, and outdoor construction is sufficient, which is very friendly to construction personnel.

[0051] The protective coating of the present invention is green and environmentally friendly, does not contain solvents, has a fast curing speed, is easy to construct, and can be basically cured after 2 hours of spraying, saving a lot of time and cost. The protective coating of the present invention has good elasticity, can undergo elastic deformation when impacted, reduce the impact force on the chassis, and spraying forms a peak structure, which can effectively disperse the impact force and has excellent noise reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a physical picture of the coating formed after spraying the protective coating in Example 1. DETAILED DESCRIPTION

[0053] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0054] The materials used in the examples and comparative examples of the present invention are as follows:

[0055] Silyl-terminated polyether S303H, silyl-terminated polyether SAX750, and dimethoxy-triethoxy mixed-terminated polyether 12000DS are all commercially available products, for example, they can be purchased from Japanese manufacturer Kaneka or domestic manufacturer Ruiyang Antai;

[0056] The particle size of ultrafine aluminum hydroxide is 0.1 to 10 μm;

[0057] Ultraviolet absorber UV-326, ultraviolet absorber UV-329, and ultraviolet absorber UV-328 can be purchased from BASF;

[0058] Light stabilizer UV-622, light stabilizer UV-292, and light stabilizer UV-770 can be purchased from BASF;

[0059] Chelated tin catalyst U-220H, whose main component is dibutyltin bis(acetylacetonate), can be purchased from Nitto Chemical Co., Ltd.

[0060] Chelated tin catalyst KRA-1, available from Kerry Chemical Company;

[0061] Silane-terminated diluent, whose main component is silane-modified polyether, is a silane-terminated polyether with a molecular weight of 1500 and a viscosity of 1.2 Pa.s, and is a low-viscosity silane-terminated reactive diluent;

[0062] The hydrophobic modified diluent is prepared by the following preparation method: selecting terminal hydroxyl polybutadiene with a weight average molecular weight of 1000-5000 as the main chain, and the plasticizer is phthalate, and weighing 22 parts by weight of terminal hydroxyl polybutadiene with a weight average molecular weight of 4000, 10 parts by weight of diisononyl phthalate, 4 parts by weight of isocyanate propyl methyl dimethoxy silane, and 0.4 parts by weight of N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxy silane respectively, and then mixing the terminal hydroxyl polybutadiene, the plasticizer and the modifier and heating to 76°C for reaction for 1h, and then cooling to 45°C and adding a capping agent for capping for 30min to prepare a hydrophobic modified diluent, and the viscosity of the hydrophobic modified diluent measured at 25°C is 0.6Pa·s.

[0063] Example 1

[0064] This example provides a protective coating, which is composed of the components in parts by weight shown in Table 1.

[0065] Table 1 Component ratio of the protective coating in Example 1

[0066]

[0067]

[0068] The protective coating in this example is prepared by a preparation method comprising the following steps:

[0069] 1) Add silyl-terminated polyether S303H, hydrophobically modified diluent, tricresyl phosphate, ultrafine aluminum hydroxide, titanium dioxide, ultraviolet absorber UV-326, light stabilizer UV-622, and polyamide wax into a planetary power mixer, stir and disperse evenly, evacuate and maintain the vacuum degree ≤-0.09Mpa, heat to 110°C, and keep warm for 3.5 hours to obtain a dry paste;

[0070] 2) The dried paste is cooled to 40° C., N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, and chelated tin catalyst U-220H are added, and stirred for 15-30 minutes to obtain the protective coating in this example.

[0071] Example 2

[0072] This example provides a protective coating, which is composed of the components in parts by weight shown in Table 2.

[0073] Table 2 Component ratio of the protective coating in Example 2

[0074]

[0075]

[0076] Example 3

[0077] This example provides a protective coating, which is composed of the components in parts by mass shown in Table 3.

[0078] Table 3 Component ratio of the protective coating in Example 3

[0079]

[0080] Comparative Example 1

[0081] This example provides a protective coating, which is composed of the components in parts by mass shown in Table 4.

[0082] Table 4 Component ratio of the protective coating in Comparative Example 1

[0083]

[0084]

[0085] Comparative Example 2

[0086] This example provides a protective coating, which is composed of the components in parts by mass shown in Table 5.

[0087] Table 5 Component ratio of the protective coating in Comparative Example 2

[0088]

[0089] The protective coatings in Examples 2 to 3 and Comparative Examples 1 to 2 can be prepared by referring to the preparation method in Example 1.

[0090] Performance Test:

[0091] According to the test methods described in HG / T 4363-2012, GB / T 10125-2021, GB / T 2408-2021, and ISO 20567-1-2017, the various properties of the coatings formed by the protective coatings in Examples 1 to 3 and Comparative Examples 1 to 2 were respectively tested, and the specific test results are shown in Table 6 below.

[0092] Table 6 Performance test results of protective coatings

[0093]

[0094]

[0095] As shown in Table 6, the protective coating in Examples 1 to 3 of the present invention introduces a hydrophobic modified diluent, which greatly improves the hydrophobic characteristics of the system, effectively reduces the erosion of the adhesive coating by rainwater, salt spray, acid, alkali, etc., and enables the coating to be firmly attached to the chassis surface, greatly improving the overall salt spray resistance, water resistance and acid and alkali resistance of the product, and effectively resisting various external erosions. At the same time, the hydrophobic modified diluent adopts silane end-capping, which can participate in the system curing reaction, improve the shear bonding strength, and greatly improve the anti-stone impact performance of the coating. Therefore, the coating formed by the protective coating in the present invention has very high shear bonding strength and stone impact resistance, and also has excellent hardness (higher hardness is conducive to improving stone impact resistance and impact damage resistance), moisture resistance, water resistance, salt spray resistance, acid and alkali resistance, and flame retardancy. Comparative Example 1 does not use a hydrophobic modified diluent, but uses a traditional diluent diisononyl phthalate instead, and increases the amount of the main resin silyl-terminated polyether S303H, and the mechanical properties, moisture resistance, water resistance, salt spray resistance, acid and alkali resistance, stone impact resistance, etc. of the coating are all deteriorated. Comparative Example 2 is a typical silane-modified protective coating, which uses a common reactive silane-terminated diluent. The coating has excellent mechanical properties and stone impact resistance, but the salt spray resistance, acid and alkali resistance, and flame retardancy of the coating are all poor.

[0096] The protective coating in Example 1 of the present invention is sprayed on a 1 mm thick stainless steel plate to form a 1 mm thick coating of Example 1, as shown in the actual figure. Figure 1 As shown, PVC (polyvinyl chloride) was coated on a new 1 mm thick stainless steel plate to form a 1 mm thick PVC coating. At the same time, the coating, PVC coating and uncoated stainless steel plate (1 mm thick) in Example 1 were tested for impact collision noise reduction effect. The specific test method is: the coating is placed upward, a 20 g weight is taken, and it falls freely at a height of 300 mm from the coating. The noise decibel generated when the weight collides is tested by a digital noise meter, and the test results are recorded in Table 7.

[0097] Table 7 Noise reduction performance test results

[0098] Test items Example 1 Coating PVC coating Uncoated stainless steel sheet Noise / dB 73 95 102

[0099] From Table 7 and Figure 1It can be seen that the coating formed by the protective coating in Example 1 of the present invention has a good silencing and noise reduction effect. The reason is that the coating formed by the coating in the present invention has good elasticity, can undergo elastic deformation when impacted, absorb and disperse part of the impact force, avoid rigid collision, and has an excellent silencing and noise reduction effect. In addition, the spraying forms a peak structure (see Figure 1 ), can effectively disperse the impact force, and has excellent noise reduction effect. The test results show that Examples 2 to 3 have basically the same noise reduction effect as Example 1.

[0100] In summary, the present invention, by compounding flame retardant plasticizers with inorganic flame retardant fillers and combining hydrophobic modified diluents, enables the coating formed by the protective coating to have excellent elasticity, flame retardancy, salt spray resistance, acid and alkali resistance, stone impact resistance, moisture resistance and other properties, and its flame retardancy grade reaches FV-0, which can meet the flame retardancy requirements on the battery chassis of new energy vehicles and promote the development of automobile chassis armor technology. In addition, the raw materials used in the protective coating of the present invention are non-toxic, green and environmentally friendly, and do not contain solvents. The formed coating has high bonding strength and excellent spray construction properties. No exclusive spray room is required, and outdoor construction is sufficient, which is very friendly to construction personnel.

[0101] In addition, the protective coating of the present invention has a fast curing speed and is easy to construct. It can be basically cured after 2 hours of spraying, saving a lot of time and cost. The protective coating of the present invention has good elasticity and can undergo elastic deformation when impacted, reducing the impact force on the chassis. The peak structure formed by spraying can effectively disperse the impact force and has excellent noise reduction effect.

[0102] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A protective coating, characterized in that: The invention comprises the following components in parts by weight: 60-100 parts of silane-terminated polyether, 40-70 parts of hydrophobically modified diluent, 50-90 parts of flame retardant plasticizer, 180-240 parts of flame retardant filler, 10-20 parts of pigment, 0.5-5 parts of ultraviolet absorber, 0.5-5 parts of light stabilizer, 1-10 parts of thixotropic agent, 1-10 parts of silane dehydrating agent, 1-10 parts of silane coupling agent and 0.1-3 parts of catalyst.

2. The protective coating according to claim 1, characterized in that: The silane-terminated polyether includes at least one of silyl-terminated polyether, dimethoxy-triethoxy mixed-terminated polyether, dimethoxy-terminated polyether, and triethoxy-terminated polyether.

3. The protective coating according to claim 1, characterized in that: The hydrophobic modified diluent comprises the following raw materials in parts by weight: 15-40 parts of terminal hydroxyl polybutadiene, 5-20 parts of plasticizer, 1-10 parts of modifier, and 0.1-3 parts of end-capping agent; the modifier is isocyanate silane; and the end-capping agent is aminohydrocarbon silane.

4. The protective coating according to claim 3, characterized in that: The plasticizer includes phthalates; And / or, the modifier includes at least one of isocyanate propyl methyl dimethoxy silane and isocyanate propyl triethoxy silane; And / or, the end-capping agent includes at least one of aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, and γ-aminopropylmethyldiethoxysilane.

5. The protective coating according to claim 3, characterized in that: The hydrophobically modified diluent is prepared by a preparation method comprising the following steps: mixing raw materials including terminal hydroxyl polybutadiene, a plasticizer and a modifier at 70-80° C., and then mixing with a capping agent at a temperature not exceeding 50° C. to prepare the hydrophobically modified diluent.

6. The protective coating according to claim 1, characterized in that: The flame retardant plasticizer includes a phosphate plasticizer; and / or the silane dehydrating agent includes at least one of vinyl trimethoxy silane, vinyl triethoxy silane, and vinyl dimethoxy silane; And / or, the catalyst comprises an organotin catalyst.

7. The method for preparing the protective coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: heating and mixing raw materials including silane-terminated polyether, hydrophobically modified diluent, flame retardant plasticizer, flame retardant filler, pigment, ultraviolet absorber, light stabilizer and thixotropic agent to obtain a paste; S2: mixing the paste with a silane dewatering agent, a silane coupling agent and a catalyst to obtain the protective coating.

8. The method for preparing the protective coating according to claim 7, characterized in that: The temperature of the heating mixing reaction in step S1 is 100-120°C; And / or, the time of the temperature-raising mixing reaction in step S1 is 2 to 4 hours; and / or, the mixed reaction temperature in step S2 does not exceed 50° C.; And / or, the mixing reaction time in step S2 is 10 to 60 minutes.

9. An automobile, comprising a chassis, characterized in that: The chassis surface is provided with a coating; the coating is formed by curing the protective coating according to any one of claims 1 to 6.

10. Use of the protective coating according to any one of claims 1 to 6 in the field of transportation vehicles.

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