A bottom-integrated coating material for engines and its preparation method

Abstract

The present invention belongs to the technical field of coatings, and particularly relates to a one-coat material for engine bottom and its preparation method. The coating material uses polyaspartate resin, introduces a rigid polysulfone chain segment to restrict the excessive movement of the flexible chain segment of the resin and improve the crosslinking density of the polymer, thereby enhancing the intermolecular force, improving the efficiency of molecular chain transfer and dissipation of energy, and further improving the impact resistance of the material; introduces a hydrophobic polymethacrylate chain segment to endow the coating with good water resistance; fills with nano titanium diboride to improve the wear resistance and corrosion resistance of the coating. The coating prepared by the present invention is a low-VOC one-coat material, which not only has good adhesion of the primer and can firmly adhere to the surface of the substrate, but also has the properties such as water resistance and corrosion resistance of the topcoat; at the same time, it reduces the emission of VOCs, helps to reduce air pollution, and meets the requirements of environmental protection policies.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and particularly relates to a one-coat system coating material for engines and a preparation method thereof. Background Art

[0002] In the traditional separate primer and topcoat coating system, due to the mismatch between the properties of the primer and the topcoat, the overall protection performance cannot reach the optimal state. As the engine operates, the coating is prone to problems such as damage and corrosion, which affect the normal operation and appearance quality of the engine. By using a one-coat system coating, it can simultaneously provide the rust prevention and corrosion protection functions of the primer and the decoration and weather resistance functions of the topcoat, and can protect the coated object for a long time under different environmental conditions. Moreover, since the one-coat system coating is formed by a one-time coating, there is no interface problem between the primer and the topcoat, and the integrity and compactness of the coating are better. This makes the coating have better anti-permeation performance, can effectively prevent the intrusion of moisture, oxygen, chemical substances, etc., improves the protection effect of the coating, and reduces the production cost.

[0003] Chinese Patent with the authorized publication number CN 115975485 B discloses an aqueous one-coat system coating. This invention copolymerizes epoxy resin, vinyl monomer and silicone to obtain an epoxy acrylate aqueous dispersion, and adds rust-inhibiting pigments, coloring pigments, fillers, anti-flash rust agents, hydrophobic agents and other additives. The obtained coating can avoid the potential problem of reduced weather resistance caused by the migration of anti-aging additives in the coating, and can improve the wettability of the coating with the substrate after curing. It has a long protection period and meets the coating requirements of vehicle parts. However, the coating of epoxy acrylate aqueous dispersion is sensitive to construction conditions, and both temperature and humidity will affect the performance of the coating. At low temperatures, the drying time of the coating is prolonged, and sagging will occur. At high temperatures, the water volatilizes too fast, and defects are likely to form on the surface of the coating.

[0004] Chinese Patent Application with the publication number CN 110205030 A discloses an aqueous one-coat system coating and a preparation method thereof. This coating mixes polyvinylidene chloride and a modified copolymer emulsion, and adds fillers such as mica powder, feldspar powder, silica, zirconia, and additives such as anti-flash rust agents, fungicides, and film-forming agents. The obtained coating has stable chemical properties and antioxidant properties, low thermal conductivity, strong impact resistance, and can provide long-term protection in an 80°C environment. The drying characteristics of polyvinylidene chloride are quite different from those of the modified copolymer emulsion, which makes the overall drying of the coating sensitive to environmental conditions. Moreover, various fillers increase the viscosity of the coating and reduce its fluidity, and it is easy to leave brush marks, roller marks or uneven spraying marks during construction, affecting the appearance flatness and aesthetics of the coating, especially in the case of large-area construction or high surface quality requirements, the problem is more obvious. Summary of the Invention

[0005] The present invention aims to provide a bottom-merged coating material for engines and a preparation method thereof. The coating material is a bottom-merged coating material for engines, which has good properties such as high temperature resistance, wear resistance, weather resistance, and corrosion resistance. Moreover, the coating is formed by one-time painting, with better integrity and compactness, longer service life. At the same time, the water-based coating can reduce the volatilization of organic compounds and avoid potential risks to the environment and human health.

[0006] To achieve the above object, the present invention provides a bottom-merged coating material for engines. The coating material includes a modified resin, water, a dispersant, nano-fillers, pigments, an antifoaming agent, a thickener, and an antioxidant. The mass ratio of the modified resin, water, dispersant, nano-fillers, pigments, antifoaming agent, thickener, and antioxidant is 1:(5 - 6):(0.1 - 0.5):(0.05 - 0.1):(0.01 - 0.03):(0.05 - 0.1):(0.01 - 0.02):(0.02 - 0.04). The modified resin is a methyl methacrylate-modified polyaspartate resin containing a polysulfone segment. The preparation method of the modified resin is as follows: Using diisopropyl fumarate and 4,4'-methylenebis(2-aminophenol) as raw materials, copolymerize to obtain a polyaspartate resin, then copolymerize with methyl methacrylate to introduce a methyl methacrylate segment, and finally copolymerize with 4,4'-dichlorodiphenyl sulfone to introduce a polysulfone segment.

[0007] Preferably, the structural formula of the modified resin is as follows:

[0008] ,

[0009] where n is an integer between 1 and 10, and m is an integer between 1 and 20.

[0010] Preferably, the nano-fillers are nano titanium diboride; the pigments are any one or more of zinc phosphate, aluminum tripolyphosphate, and zinc powder.

[0011] Preferably, the dispersant is any one or more of sodium alkyl naphthalene sulfonate, sodium diisopropyl naphthalene sulfonate, and sodium dibutyl naphthalene sulfonate.

[0012] Preferably, the antifoaming agent is polyoxyethylene polyoxypropylene ether.

[0013] Preferably, the antioxidant is any one or more of 2,6-di-tert-butyl-4-methylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and dilauryl thiodipropionate.

[0014] Preferably, the thickener is any one or more of methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose.

[0015] The present invention also provides a preparation method of a bottom and surface integrated coating material for an engine, including:

[0016] Step S1: Dissolve diisopropyl fumarate and 4,4'-methylenebis(2-aminophenol) in a first solvent, and react to obtain a polyaspartic acid ester resin;

[0017] Step S2: Mix the polyaspartic acid ester resin with methyl methacrylate, dissolve in a second solvent, add an initiator, and react to obtain a methyl methacrylate-modified polyaspartic acid ester resin;

[0018] Step S3: Disperse the methyl methacrylate-modified polyaspartic acid ester resin in a second solvent, add sodium hydroxide, and react to obtain a disodium salt intermediate of the methyl methacrylate-modified polyaspartic acid ester resin;

[0019] Step S4: Dissolve the disodium salt intermediate obtained in Step S3 and 4,4'-dichlorodiphenyl sulfone in a first solvent, add a catalyst, and react to obtain a methyl methacrylate-modified polyaspartic acid ester resin containing a polysulfone segment;

[0020] Step S5: Dissolve a dispersant in deionized water, add a pigment, a nano filler, an antifoaming agent, a thickener, and a resin, and stir to obtain a bottom and surface integrated coating material for an engine.

[0021] Preferably, the first solvent is any one or more of dimethyl sulfoxide, N,N'-dimethylformamide, and acetone.

[0022] Preferably, the second solvent is any one or more of ethyl acetate, acetone, and toluene.

[0023] Preferably, in Step S1, the mass ratio of diisopropyl fumarate, 4,4'-methylenebis(2-aminophenol), and the first solvent is 1:(2-3):(3-4).

[0024] Preferably, in Step S1, the reaction temperature is 40-80°C, and the reaction time is 3-6 h.

[0025] Preferably, in Step S2, the initiator is any one or more of benzoyl peroxide, di-tert-butyl peroxide, and azobisisobutyronitrile.

[0026] Preferably, in Step S2, the mass ratio of the polyaspartic acid ester resin, methyl methacrylate, initiator, and the second solvent is 1:(0.38-0.5):(0.01-0.05):(3-5)

[0027] Preferably, in Step S2, the reaction temperature is 40-60°C, and the reaction time is 5-8 h.

[0028] Preferably, in the step S3, the mass ratio of the methacrylic acid-modified polyaspartic acid ester resin, sodium hydroxide, and the second solvent is 1: (0.14 - 0.2): (2 - 3).

[0029] Preferably, in the step S3, the reaction temperature is 40 - 60 °C, and the reaction time is 3 - 5 h.

[0030] Preferably, in the step S4, the catalyst is any one or more of potassium carbonate and tetrabutylammonium bromide.

[0031] Preferably, in the step S4, the mass ratio of the disodium salt intermediate, 4,4'-dichlorodiphenyl sulfone, the catalyst, and the first solvent is 1: (1 - 1.2): (0.05 - 0.2): (3 - 4).

[0032] Preferably, in the step S4, the reaction temperature is 60 - 80 °C, and the reaction time is 8 - 12 h.

[0033] Preferably, in the step S5, the stirring temperature is 25 - 45 °C, and the stirring time is 15 - 30 min.

[0034] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0035] (1) To improve the high-temperature resistance and impact resistance of the coating, the present invention uses polyaspartic acid ester resin and introduces polysulfone and polymethacrylic acid segments. The polyaspartic acid ester resin itself has a flexible chain segment structure. By introducing the polysulfone segment with a rigid structure, through intermolecular forces such as van der Waals forces and hydrogen bonds, the tightness between molecular chains is enhanced, effectively restricting the excessive movement of the flexible chain segments of the polyaspartic acid ester resin. When the material is subjected to impact, the movement of the flexible chain segments becomes more orderly, and the force is better dispersed into the system, avoiding energy concentration in a local area and causing the material to break. The polymethacrylic acid segment forms a crosslink with the polyaspartic acid ester resin, enhancing the interaction between molecular chains, and quickly transmitting and dissipating energy through the molecular chains, thereby improving the impact resistance of the material.

[0036] (2) To improve the high-temperature resistance of the coating, the present invention introduces a polysulfone segment. The introduced polysulfone segment contains structural units such as benzene rings, sulfone groups, and ether bonds. The covalent bond formed between the sulfone group and the aryl group has a high bond energy, and the conjugation effect generated by the benzene ring and olefin structure makes the overall electron cloud of the polymer have better delocalization, reducing the system energy and making the structure more stable, thereby improving the overall thermal stability of the polymer.

[0037] (3) To improve the wear resistance and corrosion resistance of the coating, the present invention is achieved by adding titanium diboride nanoparticles. The titanium diboride nanoparticles are uniformly dispersed in the coating, forming a physical barrier, and at the same time filling the voids and defects in the coating, making the coating structure more dense, reducing its dissolution rate and chemical reaction activity in the corrosive medium. Description of the Drawings

[0038] Figure 1 It is a preparation flow chart of a bottom-in-one coating material for an engine.

[0039] Figure 2 It is a synthesis route of a polysulfone segment-containing modified polymethacrylate-modified polyaspartate resin.

[0040] Figure 3 It is a scanning electron microscope picture of the bottom-in-one coating material for an engine prepared in Example 3. Specific Embodiments

[0041] The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

[0042] The main compounds used in the examples and comparative examples are all commercially available products and have not been subjected to any further purification treatment.

[0043] Example 1

[0044] As Figure 1 shown, a bottom-in-one coating material for an engine, its preparation method includes:

[0045] Step S1: Weigh 10 g of diisopropyl fumarate, mix it with 20 g of 4,4'-methylenebis(2-aminophenol), dissolve it in 30 g of dimethyl sulfoxide, and react at 40 °C for 6 h to obtain a polyaspartate resin.

[0046] Step S2: Weigh 10 g of the polyaspartate resin, mix it with 3.8 g of methyl methacrylate, dissolve it in 30 g of ethyl acetate, add 0.1 g of benzoyl peroxide, and react at 40 °C for 8 h to obtain a polymethacrylate-modified polyaspartate resin.

[0047] Step S3: Weigh 10 g of the polymethacrylate-modified polyaspartate resin, disperse it in 20 g of ethyl acetate, add 1.4 g of sodium hydroxide, and react at 40 °C for 5 h to obtain a disodium salt intermediate of the polymethacrylate-modified polyaspartate resin.

[0048] Step S4: Weigh 10 g of the disodium salt intermediate obtained in Step S3, mix it with 10 g of 4,4'-dichlorodiphenyl sulfone, dissolve it in 30 g of dimethyl sulfoxide, add 0.5 g of potassium carbonate, and react at 60 °C for 10 h to obtain a methacrylic acid-modified polyaspartate resin containing a polysulfone segment.

[0049] Step S5: Weigh 1 g of alkylnaphthalenesulfonate, dissolve it in 50 g of deionized water, add 0.1 g of zinc phosphate, 0.5 g of nano-titanium diboride, 0.5 g of polyoxyethylene polyoxypropylene ether, 0.2 g of 2,6-di-tert-butyl-4-methylphenol, 0.1 g of methyl cellulose, and 10 g of the modified resin, and stir at 25 °C for 30 min to obtain a bottom-coalescing coating material for engines.

[0050] Example 2

[0051] As Figure 1 shown, a preparation method of a bottom-coalescing coating material for engines includes the following steps:

[0052] Step S1: Weigh 10 g of diisopropyl fumarate, mix it with 25 g of 4,4'-methylenebis(2-aminophenol), dissolve it in 40 g of N,N'-dimethylformamide, and react at 60 °C for 4 h to obtain a polyaspartate resin.

[0053] Step S2: Weigh 10 g of the polyaspartate resin, mix it with 4.5 g of methyl methacrylate, dissolve it in 40 g of acetone, add 0.3 g of di-tert-butyl peroxide, and react at 50 °C for 6 h to obtain a methacrylic acid-modified polyaspartate resin.

[0054] Step S3: Weigh 10 g of the methacrylic acid-modified polyaspartate resin, disperse it in 25 g of an acetone solution, add 1.8 g of sodium hydroxide, and react at 50 °C for 4 h to obtain a disodium salt intermediate of the methacrylic acid-modified polyaspartate resin.

[0055] Step S4: Weigh 10 g of the disodium salt intermediate obtained in Step S3, mix it with 11 g of 4,4'-dichlorodiphenyl sulfone, dissolve it in 40 g of N,N'-dimethylformamide, add 1 g of potassium carbonate, and react at 70 °C for 9 h to obtain a methacrylic acid-modified polyaspartate resin containing a polysulfone segment.

[0056] Step S5: Weigh 3 g of sodium diisopropylnaphthalenesulfonate, dissolve it in 60 g of deionized water, add 0.2 g of aluminum tripolyphosphate, 0.75 g of nano titanium diboride, 0.75 g of polyoxyethylene polyoxypropylene ether, 0.3 g of tris(2,4-di-tert-butylphenyl) phosphite, 0.2 g of carboxymethyl cellulose, and 10 g of modified resin, and stir at 35 °C for 20 min to obtain a bottom-in-one coating material for engines.

[0057] Example 3

[0058] As Figure 1 shown, a preparation method of a bottom-in-one coating material for engines includes the following steps:

[0059] Step S1: Weigh 10 g of diisopropyl fumarate, mix it with 30 g of 4,4'-methylenebis(2-aminophenol), dissolve it in 40 g of acetone, and react at 80 °C for 3 h to obtain a polyaspartate resin.

[0060] Step S2: Weigh 10 g of the polyaspartate resin, mix it with 5 g of methyl methacrylate, dissolve it in 50 g of toluene, add 0.5 g of azobisisobutyronitrile, and react at 60 °C for 5 h to obtain a methyl methacrylate-modified polyaspartate resin.

[0061] Step S3: Weigh 10 g of the methyl methacrylate-modified polyaspartate resin, disperse it in 30 g of toluene solution, add 2 g of sodium hydroxide, and react at 60 °C for 3 h to obtain a disodium salt intermediate of the methyl methacrylate-modified polyaspartate resin.

[0062] Step S4: Weigh 10 g of the disodium salt intermediate obtained in Step S3, mix it with 12 g of 4,4'-dichlorodiphenyl sulfone, dissolve it in 40 g of acetone, add 2 g of potassium carbonate, and react at 80 °C for 8 h to obtain a methyl methacrylate-modified polyaspartate resin containing a polysulfone segment.

[0063] Step S5: Weigh 5 g of sodium dibutylnaphthalenesulfonate, dissolve it in 60 g of deionized water, add 0.3 g of zinc powder, 1 g of nano titanium diboride, 1 g of polyoxyethylene polyoxypropylene ether, 0.4 g of dilauryl thiodipropionate, 0.2 g of hydroxyethyl cellulose, and 10 g of modified resin, and stir at 45 °C for 15 min to obtain a bottom-in-one coating material for engines. The scanning electron micrograph is as Figure 3 shown.

[0064] Comparative Example 1

[0065] A preparation method of a bottom-merged coating material for an engine, which is different from Example 3 in that methyl methacrylate is not added in step S2.

[0066] Comparative Example 2

[0067] A preparation method of a bottom-merged coating material for an engine, which is different from Example 3 in that 4,4'-dichlorodiphenyl sulfone is not added in step S4.

[0068] Comparative Example 3

[0069] A preparation method of a bottom-merged coating material for an engine, which is different from Example 3 in that nano titanium diboride is not added in step S5.

[0070] Performance test: Test the impact resistance (GB / T 1732), water resistance (GB / T 1733), adhesion (GB / T 9286), salt spray resistance (GB / T 10125), and abrasion resistance (GB / T 1768) of the coating materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3.

[0071] Table 1 Impact resistance test data of the coating

[0072]

[0073] According to the data in Table 1, the impact resistance of the coating materials prepared in Examples 1 to 3 is all above 50, and their impact resistance performance is better than that of the coating materials prepared in Comparative Examples 1 to 3. Experiments prove that by using the method of the examples, introducing polysulfone chain segments and polymethacrylate chain segments into the polyaspartic acid ester resin can effectively improve the impact resistance performance of the resin.

[0074] Table 2 Water resistance test results of the coating

[0075]

[0076] According to Table 2, the coating materials prepared in Examples 1 to 3 have not changed in normal temperature water and boiling water, proving that the coating materials have good water resistance and high temperature resistance. The coating materials prepared in Comparative Example 1 and Comparative Example 3 show wrinkling and peeling in normal temperature water, and the coating materials prepared in Comparative Example 1 and 2 show discoloration, wrinkling and peeling in waste water, and Comparative Example 3 shows discoloration, wrinkling and peeling. Experiments prove that the lack of polymethacrylate structure in the coating material reduces the hydrophobicity of the material, and the lack of polysulfone chain segments weakens the high temperature resistance of the material.

[0077] Table 3 Adhesion test data of the coating

[0078]

[0079] Note: The criteria for judging the adhesion test from level 0 to level 5 are as follows: Level 0: No peeling. Level 1: The peeling area does not exceed 5%. Level 2: The peeling area is between 5% and 15%. Level 3: The peeling area is between 15% and 35%. Level 4: The peeling area is between 35% and 65%. Level 5: The peeling area is greater than 65%.

[0080] As shown in Table 3, the adhesion of the coating materials prepared in Examples 1 to 3 can be judged as Grade 0, and the coating adhesion is excellent, and there is no risk of falling off. The coating materials prepared in Comparative Examples 1 and 3 can be judged as Grade 1, with a falling off area of less than 5%, and good adhesion. The coating material prepared in Comparative Example 2 has a falling off area between 5 and 15%, which is judged as Grade 2. Experiments have shown that the use of polyaspartic acid ester resin and the introduction of polysulfone segments and polymethacrylate segments can increase the crosslinking density of the resin, thereby enhancing the adhesion of the resin.

[0081] Table 4 Test results of coating salt spray resistance

[0082]

[0083] Note: The judgment criteria of 1~10 in the salt spray resistance test are as follows: 10: No visible changes. 8~9: Slight discoloration or a small number of very fine corrosion spots. 6~7: Obvious discoloration, a small number of corrosion spots with a small diameter or slight blistering. 4~5: Severe discoloration, an increase in the number of corrosion spots and a larger diameter, blistering, and slight peeling. 2~3: Severe discoloration, a large number of corrosion spots connected into pieces, severe blistering, and obvious peeling. 1: Almost completely corroded.

[0084] As shown in Table 4, the salt spray resistance of the coating materials prepared in Examples 1 to 3 can be judged as level 10, and the treated coating materials show no visible changes. The coating materials prepared in Comparative Examples 1 and 2 show fine corrosion spots, which are judged as level 8 to 9. The coating material prepared in Comparative Example 3 shows obvious discoloration, corrosion spots with larger diameters, and slight shedding, which is judged as level 4 to 5. Experiments have shown that the addition of nano-titanium diboride can significantly improve the salt spray resistance of the material.

[0085] Table 5 Test data of coating wear resistance

[0086]

[0087] As shown in Table 5, the coating materials prepared in Example 1 and Example 2 showed slight wear after 8,000 times of polishing and obvious wear after 10,000 times of polishing. The coating prepared in Example 3 showed slight wear after 9,000 times of polishing and obvious wear after 10,000 times of polishing. Comparative Example 3 showed slight wear after 4,000 times of polishing, the coating warped after 6,000 times of polishing, and peeled off after 8,000 times of polishing. Comparative Example 2 showed slight wear after 5,000 times of polishing, the coating warped after 7,000 times of polishing, and peeled off after 8,000 times of polishing. The comparative example showed slight wear after 6,000 times of polishing, the coating warped after 8,000 times of polishing, and peeled off after 9,000 times of polishing. Compared with Comparative Examples 1 to 3, the coatings prepared in Examples 1 to 3 have better wear resistance. Experiments have proved that by using polyaspartic ester resin, introducing polysulfone and polymethacrylate chain segments, improving the crosslinking density of the resin structure, and adding nano titanium diboride, the wear resistance of the material can be significantly improved.

[0088] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A bottom-integrated coating material for an engine, characterized in that, The coating material includes a modified resin, water, a dispersant, nano-fillers, pigments, an antifoaming agent, a thickener, and an antioxidant; the mass ratio of the modified resin, water, dispersant, nano-fillers, pigments, antifoaming agent, thickener, and antioxidant is 1:(5 - 6):(0.1 - 0.5):(0.05 - 0.1):(0.01 - 0.03):(0.05 - 0.1):(0.01 - 0.02):(0.02 - 0.04); the modified resin is a methyl methacrylate-modified polyaspartate resin containing a polysulfone segment, and the preparation method of the modified resin is as follows: Using diisopropyl fumarate and 4,4'-methylenebis(2-aminophenol) as raw materials, copolymerize to obtain a polyaspartate resin, then copolymerize with methyl methacrylate to introduce a methyl methacrylate segment, and finally copolymerize with 4,4'-dichlorodiphenyl sulfone to introduce a polysulfone segment.

2. The bottom surface integrated coating material for an engine according to claim 1, characterized in that The structural formula of the modified resin is as follows: ， Among them, n takes an integer value between 1 and 10, and m takes an integer value between 1 and 20.

3. The bottom surface integrated coating material for an engine according to claim 1, wherein The nano-fillers are nano-titanium diboride; the pigments are any one or more of zinc phosphate, aluminum tripolyphosphate, and zinc powder; the dispersant is any one or more of sodium alkylnaphthalene sulfonate, sodium diisopropylnaphthalene sulfonate, and sodium dibutylnaphthalene sulfonate.

4. A bottom-integrated coating material for an engine according to claim 1, characterized in that The antifoaming agent is polyoxyethylene polyoxypropylene ether; the thickener is any one or more of methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose; the antioxidant is any one or more of 2,6-di-tert-butyl-4-methylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and dilauryl thiodipropionate.

5. The preparation method of a bottom-integrated coating material for an engine according to any one of claims 1 to 4, characterized in that, It includes the following steps: Step S1: Dissolve diisopropyl fumarate and 4,4'-methylenebis(2-aminophenol) in a first solvent and react to obtain a polyaspartate resin; Step S2: Mix the polyaspartate resin with methyl methacrylate, dissolve it in a second solvent, add an initiator, and react to obtain a methyl methacrylate-modified polyaspartate resin; Step S3: Disperse the methyl methacrylate-modified polyaspartate resin in a second solvent, add sodium hydroxide, and react to obtain a disodium salt intermediate of the methyl methacrylate-modified polyaspartate resin; Step S4: Dissolve the disodium salt intermediate obtained in Step S3 and 4,4'-dichlorodiphenyl sulfone in a first solvent, add a catalyst, and react to obtain a methyl methacrylate-modified polyaspartate resin containing a polysulfone segment; Step S5: Dissolve the dispersant in deionized water, add pigments, nano-fillers, an antifoaming agent, a thickener, an antioxidant, and the methyl methacrylate-modified polyaspartate resin containing a polysulfone segment prepared in Step S4, and stir to obtain a bottom-in-one coating material for the engine.

6. The preparation method of a bottom-integrated coating material for an engine according to claim 5, characterized in that, The first solvent is any one or more of dimethyl sulfoxide, N, N'-dimethylformamide, and acetone; the second solvent is any one or more of ethyl acetate, acetone, and toluene; the initiator is any one or more of benzoyl peroxide, di-tert-butyl peroxide, and azobisisobutyronitrile; in the step S1, the mass ratio of diisopropyl fumarate, 4,4'-methylenebis(2-aminophenol), and the first solvent is 1:(2-3):(3-4); the reaction temperature is 40-80 °C, and the reaction time is 3-6 h.

7. The preparation method of a bottom-integrated coating material for an engine according to claim 5, characterized in that, In the step S2, the mass ratio of the polyaspartate resin, methyl methacrylate, the initiator, and the second solvent is 1:(0.38-0.5):(0.01-0.05):(3-5); the reaction temperature is 40-60 °C, and the reaction time is 5-8 h.

8. The preparation method of a bottom-integrated coating material for an engine according to claim 5, characterized in that, In the step S3, the mass ratio of the methyl methacrylate-modified polyaspartate resin, sodium hydroxide, and the second solvent is 1:(0.14-0.2):(2-3); the reaction temperature is 40-60 °C, and the reaction time is 3-5 h.

9. The preparation method of a bottom-integrated coating material for an engine according to claim 5, characterized in that, In the step S4, the catalyst is any one or more of potassium carbonate and tetrabutylammonium bromide; the mass ratio of the disodium salt intermediate, 4,4'-dichlorodiphenyl sulfone, the catalyst, and the first solvent is 1:(1-1.2):(0.05-0.2):(3-4); the reaction temperature is 60-80 °C, and the reaction time is 8-12 h.

10. The preparation method of a bottom-integrated coating material for an engine according to claim 5, characterized in that, In the step S5, the stirring temperature is 25-45 °C, and the stirring time is 15-30 min.

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