Primer-topcoat coating material for engine and preparation method of primer-topcoat coating material

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a primer-topcoat coating material for an engine and a preparation method of the primer-topcoat coating material. According to the coating material, polyaspartic acid ester resin is adopted, a rigid polysulfone chain segment is introduced, excessive movement of a flexible chain segment of the resin is limited, and the crosslinking density of a polymer is improved, so that the intermolecular acting force is enhanced, the efficiency of molecular chain transfer and energy dissipation is improved, and the impact resistance of the material is further improved; a hydrophobic polymethacrylate chain segment is introduced, so that the paint is endowed with good water resistance; the nano titanium diboride is filled, so that the wear resistance and the corrosion resistance of the coating are improved. The coating prepared by the invention is a primer-topcoat low-VOC coating, has good adhesive force of a primer, can be firmly attached to the surface of a base layer, and also has water resistance, corrosion resistance and other properties of a topcoat; meanwhile, emission of VOC is reduced, air pollution can be reduced, and the requirements of environmental protection policies are met.

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. With the operation of the engine, problems such as coating breakage and corrosion are likely to occur, thus affecting 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 enables the coating to have better anti-permeation performance, effectively preventing the intrusion of moisture, oxygen, chemical substances, etc., improving the protection effect of the coating, and reducing 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, water repellents and other additives. The obtained coating can avoid the potential risk of reduced weather resistance caused by the migration of anti-aging additives in the coating, and can also improve the wettability between the cured coating and the substrate. 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, film-forming agents, etc. 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 will cause the overall drying of the coating to be 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 one - coat - fits - all coating material for engines and its preparation method. The coating material is a one - coat - fits - all 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 - mentioned purpose, the present invention provides a one - coat - fits - all 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 polyaspartic acid ester 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 polyaspartic acid ester 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: , where n is an integer between 1 and 10, and m is an integer between 1 and 20.

[0008] Preferably, the nano - filler is nano - titanium diboride; the pigment is any one or more of zinc phosphate, aluminum tripolyphosphate, and zinc powder.

[0009] Preferably, the dispersant is any one or more of sodium alkylnaphthalene sulfonate, sodium diisopropylnaphthalene sulfonate, and sodium dibutylnaphthalene sulfonate.

[0010] Preferably, the antifoaming agent is polyoxyethylene polyoxypropylene ether.

[0011] 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.

[0012] Preferably, the thickener is any one or more of methyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose.

[0013] The present invention also provides a preparation method for the one - coat - fits - all coating material for engines, including: 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 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 a dispersant in deionized water, add a pigment, a nano filler, an antifoaming agent, a thickening agent, and a resin, and stir to obtain a one-coat bottom surface coating material for an engine.

[0014] Preferably, the first solvent is any one or more of dimethyl sulfoxide, N,N'-dimethylformamide, and acetone.

[0015] Preferably, the second solvent is any one or more of ethyl acetate, acetone, and toluene.

[0016] 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).

[0017] Preferably, in Step S1, the reaction temperature is 40 - 80°C, and the reaction time is 3 - 6 h.

[0018] Preferably, in Step S2, the initiator is any one or more of benzoyl peroxide, di-tert-butyl peroxide, and azobisisobutyronitrile.

[0019] Preferably, in Step S2, the mass ratio of the polyaspartate resin, methyl methacrylate, initiator, and the second solvent is 1:(0.38 - 0.5):(0.01 - 0.05):(3 - 5). Preferably, in Step S2, the reaction temperature is 40 - 60°C, and the reaction time is 5 - 8 h.

[0020] Preferably, in 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).

[0021] Preferably, in the step S3, the reaction temperature is 40~60°C and the reaction time is 3~5 h.

[0022] Preferably, in the step S4, the catalyst is any one or more of potassium carbonate and tetrabutylammonium bromide.

[0023] 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).

[0024] Preferably, in the step S4, the reaction temperature is 60~80°C and the reaction time is 8~12 h.

[0025] Preferably, in the step S5, the stirring temperature is 25~45°C and the stirring time is 15~30 min.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) To improve the high-temperature resistance and impact resistance of the coating, the present invention uses polyaspartate resin and introduces polysulfone and polymethacrylic acid segments. The polyaspartate resin itself has a flexible chain segment structure. By introducing the polysulfone chain 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 polyaspartate 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 material rupture. The polymethacrylic acid segment forms a crosslink with the polyaspartate resin, enhancing the interaction between molecular chains and quickly transferring and dissipating energy through the molecular chains, thereby improving the impact resistance of the material.

[0027] (2) To improve the high-temperature resistance of the coating, the present invention introduces a polysulfone chain segment. The introduced polysulfone chain 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.

[0028] (3) To improve the wear resistance and corrosion resistance of the coating, the present invention is achieved by adding nano-titanium diboride. Nano-titanium diboride is evenly dispersed in the coating, forming a physical barrier, and at the same time filling the voids and defects of the coating, making the coating structure more dense and reducing its dissolution rate and chemical reaction activity in the corrosive medium. Description of the Drawings

[0029] Figure 1It is a preparation flow chart of a bottom-in-one coating material for an engine.

[0030] Figure 2 It is a synthesis route of a methyl methacrylate-modified polyaspartate resin modified with a polysulfone segment.

[0031] Figure 3 It is a scanning electron microscope picture of the bottom-in-one coating material for an engine prepared in Example 3. Specific implementation manners

[0032] 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.

[0033] 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.

[0034] Example 1 As Figure 1 shown, a bottom-in-one coating material for an engine, the preparation method thereof includes: 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.

[0035] 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 methyl methacrylate-modified polyaspartate resin.

[0036] Step S3: Weigh 10 g of the methyl methacrylate-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 methyl methacrylate-modified polyaspartate resin.

[0037] 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 methyl methacrylate-modified polyaspartate resin containing a polysulfone segment.

[0038] Step S5: Weigh 1 g of sodium alkylnaphthalene sulfonate, 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 modified resin, and stir for 30 min at 25 °C to obtain the bottom-in-one coating material for the engine.

[0039] Example 2 As Figure 1 shown, a preparation method of a bottom-in-one coating material for an engine includes the following steps: 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 polyaspartic acid ester resin.

[0040] Step S2: Weigh 10 g of the polyaspartic acid ester 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 methyl methacrylate-modified polyaspartic acid ester resin.

[0041] Step S3: Weigh 10 g of the methyl methacrylate-modified polyaspartic acid ester 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 methyl methacrylate-modified polyaspartic acid ester resin.

[0042] 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 methyl methacrylate-modified polyaspartic acid ester resin containing a polysulfone segment.

[0043] Step S5: Weigh 3 g of sodium diisopropylnaphthalene sulfonate, 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 for 20 min at 35 °C to obtain the bottom-in-one coating material for the engine.

[0044] Example 3 As Figure 1 shown, a preparation method of a bottom-in-one coating material for an engine includes the following steps: 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 polyaspartic acid ester resin.

[0045] Step S2: Weigh 10 g of the polyaspartic acid ester 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 polyaspartic acid ester resin.

[0046] Step S3: Weigh 10 g of the methyl methacrylate-modified polyaspartic acid ester resin, disperse it in 30 g of a 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 polyaspartic acid ester resin.

[0047] 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 polyaspartic acid ester resin containing a polysulfone segment.

[0048] 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 the modified resin, and stir at 45 °C for 15 min to obtain a bottom-coat-in-one coating material for engines. The scanning electron micrograph is as Figure 3 shown.

[0049] Comparative Example 1 A preparation method of a bottom-coat-in-one coating material for engines, which is different from Example 3 in that methyl methacrylate is not added in Step S2.

[0050] Comparative Example 2 A preparation method of a bottom-coat-in-one coating material for engines, which is different from Example 3 in that 4,4'-dichlorodiphenyl sulfone is not added in Step S4.

[0051] Comparative Example 3 A preparation method of a bottom-coat-in-one coating material for engines, which is different from Example 3 in that nano titanium diboride is not added in Step S5.

[0052] 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 1-3 and Comparative Examples 1-3.

[0053] Table 1 Test data of the impact resistance of the coating

[0054]

[0055] According to the data in Table 1, the impact resistance of the coating materials prepared in Examples 1-3 is all above 50, and their impact resistance performance is better than that of the coating materials prepared in Comparative Examples 1-3. Experiments prove that by adopting the method of the examples, introducing polysulfone chain segments and polymethacrylate chain segments into the polyaspartate ester resin can effectively improve the impact resistance of the resin.

[0056] Table 2 Test results of the water resistance of the coating

[0057] According to Table 2, the coating materials prepared in Examples 1-3 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 showed wrinkling and peeling in normal temperature water. The coating materials prepared in Comparative Example 1 and 2 showed discoloration, wrinkling and peeling in waste water, and Comparative Example 3 showed 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.

[0058] Table 3 Test data of the adhesion of the coating

[0059] Note: The judgment standard of 0-5 levels in the adhesion test experiment: Level 0: No peeling at all. 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%.

[0060] According to Table 3, the adhesion of the coating materials prepared in Examples 1-3 can all be judged as Level 0, the coating adhesion is excellent, and there is no risk of peeling. The coating materials prepared in Comparative Example 1 and 3 can be judged as Level 1, the peeling area is less than 5%, and the adhesion is good. For the coating material prepared in Comparative Example 2, the peeling area is between 5% and 15%, and it is judged as Level 2. Experiments prove that by using polyaspartate ester resin and introducing polysulfone chain segments and polymethacrylate chain segments, the crosslinking density of the resin can be increased, thereby enhancing the adhesion of the resin.

[0061] Table 4 Test results of coating salt spray resistance

[0062] 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.

[0063] 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.

[0064] Table 5 Test data of coating wear resistance

[0065] As shown in Table 5, the coating materials prepared in Examples 1 and 2 only produce slight wear after 8000 grindings, and produce obvious wear after 10000 grindings. The coating prepared in Example 3 shows slight wear after 9000 grindings, and shows obvious wear after 10000 grindings. Comparative Example 3 shows slight wear after 4000 grindings, the coating warps after 6000 grindings, and falls off after 8000 grindings. Comparative Example 2 shows slight wear after 5000 grindings, the coating warps after 7000 grindings, and the coating falls off after 8000 grindings. The comparative example shows slight wear after 6000 grindings, the coating warps after 8000 grindings, and the coating falls off after 9000 grindings. Compared with Comparative Examples 1 to 3, the coating prepared in Examples 1 to 3 has better wear resistance. Experiments have shown that the use of polyaspartic acid resin, the introduction of polysulfone and polymethacrylate segments, the improvement of the cross-linking density of the resin structure, and the addition of nano-titanium diboride can significantly improve the wear resistance of the material.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bottom-to-surface coating material for an engine, characterized in that: The coating material comprises a modified resin, water, a dispersant, a nanofiller, a pigment, a defoamer, a thickener and an antioxidant; the mass ratio of the modified resin, water, a dispersant, a nanofiller, a pigment, a defoamer, a thickener and an 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 methacrylic acid-modified polyaspartic acid ester resin modified with a polysulfone chain segment, and the preparation method of the modified resin is: using diisopropyl fumarate and 4, 4'-methylenebis(2-aminophenol) as raw materials, copolymerizing to obtain a polyaspartic acid ester resin, then copolymerizing with methyl methacrylate to introduce a methyl methacrylate chain segment, and finally copolymerizing with 4, 4'-dichlorodiphenyl sulfone to introduce a polysulfone chain segment.

2. The bottom-surface-in-one coating material for an engine according to claim 1, characterized in that: The modified resin structural formula is as follows: ， Wherein, n is an integer between 1 and 10, and m is an integer between 1 and 20.

3. The bottom-surface-in-one coating material for an engine according to claim 1, characterized in that: The nano filler is nano titanium diboride; the pigment is any one or more of zinc phosphate, aluminum tripolyphosphate, and zinc powder; and the dispersant is any one or more of sodium alkyl naphthalene sulfonate, sodium diisopropyl naphthalene sulfonate, and sodium dibutyl naphthalene sulfonate.

4. The bottom-surface-in-one coating material for an engine according to claim 1, characterized in that: The defoaming 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. A method for preparing a bottom-surface-in-one coating material for an engine according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1, dissolving diisopropyl fumarate and 4, 4'-methylenebis(2-aminophenol) in a first solvent, and reacting to obtain a polyaspartic acid ester resin; Step S2, mixing polyaspartic acid ester resin and methyl methacrylate, dissolving the mixture in a second solvent, adding an initiator, and reacting to obtain methacrylic acid modified polyaspartic acid ester resin; Step S3, dispersing the methacrylic acid modified polyaspartic acid ester resin in a second solvent, adding sodium hydroxide, and reacting to obtain a disodium salt intermediate of the methacrylic acid modified polyaspartic acid ester resin; Step S4, dissolving the disodium salt intermediate obtained in step S3 and 4, 4'-dichlorodiphenyl sulfone in a first solvent, adding a catalyst, and reacting to obtain a methacrylic acid-modified polyaspartic acid ester resin containing a polysulfone segment; Step S5, dissolving the dispersant in deionized water, adding pigment, nanofiller, defoamer, thickener, antioxidant, and methacrylic acid-modified polyaspartic acid ester resin containing polysulfone segments prepared in step S4, and stirring to obtain a bottom-surface integrated coating material for an engine.

6. The method for preparing a bottom-surface-in-one 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 method for preparing a bottom-surface-in-one coating material for an engine according to claim 5, characterized in that: In the 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); the reaction temperature is 40-60° C., and the reaction time is 5-8 h.

8. The method for preparing a bottom-surface-in-one coating material for an engine according to claim 5, characterized in that: 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); the reaction temperature is 40-60° C., and the reaction time is 3-5 h.

9. The method for preparing a bottom-surface-in-one 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 method for preparing a bottom-surface-in-one 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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