Antifouling and drag-reducing coating and preparation method thereof

Abstract

The invention provides a preparation method of an antifouling and drag-reducing coating, belonging to the technical field of coatings. The antifouling and drag-reducing coating comprises the following raw materials in parts by weight: 30-40 parts of an antifouling resin; 10-15 parts of a pigment; 10-25 parts of a solvent; 5-15 parts of a thickener; and 5-10 parts of a plasticizer. The invention utilizes double bonds in open-ring maleic anhydride to react with double bonds in resin A to generate an ene reaction, and the open-ring maleic anhydride is used as a bridge to graft silicon dioxide and 1,3-diglycidyl ether glycerol, wherein epoxy groups react with hydroxyl groups on a substrate to obtain a super-hydrophobic surface, and the remaining epoxy groups react with bisamino-terminated polydimethylsiloxane. The obtained coating has low surface energy, thereby improving the antifouling performance of the super-hydrophobic surface.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a method for preparing an antifouling and drag-reducing coating. Background Art

[0002] Long-term immersion of ship equipment in seawater not only exposes it to corrosion, but also exposes it to the attachment of marine microorganisms, which increases the roughness of the hull surface, increasing the ship's resistance and reducing its speed. The biological metabolism and secretions can also cover or damage the original surface of the equipment, damaging the hull coating and causing corrosion and discoloration. Therefore, research on marine drag reduction and anti-fouling is urgently needed.

[0003] By grafting long hydrophobic chains onto the coating surface, a brush-like structure is created. This structure not only reduces the adhesion of foulants but also effectively reduces the frictional resistance of water flow to the surface. Adding drag reducers to antifouling coatings can significantly improve the coating's drag-reducing properties. Drag reducers are additives that reduce internal friction during fluid flow. They are primarily polymers. Due to the inherent viscoelasticity of the polymer chains, their macromolecular chains can stretch along the direction of fluid movement. The forces between these macromolecular chains weaken the radial forces acting on the drag reducer molecules from the fluid microunits, thereby changing the magnitude and direction of the force acting on the fluid. This, in turn, alters the fluid's viscous properties on a macro scale, thereby reducing the fluid's frictional resistance.

[0004] Chinese patent publication number CN111826031A discloses a copper-free marine antifouling coating and a preparation method thereof. The raw materials of the antifouling coating include chloroether resin, rosin, pigment, zinc oxide, organic bentonite, talc, a compound antifouling agent and a mixed solvent. However, the antifouling performance of the coating is poor. Summary of the Invention

[0005] (1) Technical problems solved

[0006] The purpose of the present invention is to provide an antifouling and drag-reducing coating and a preparation method thereof, so as to solve the problem that traditional coatings have poor antifouling performance.

[0007] (2) Technical solution

[0008] This application proposes a technical solution, an antifouling and drag-reducing coating, which is prepared from the following raw materials in parts by weight:

[0009] 30-40 parts of antifouling resin;

[0010] 10~15 parts of pigment;

[0011] 10-25 parts of solvent;

[0012] 5-15 parts of thickener;

[0013] 5-10 parts of plasticizer;

[0014] The antifouling resin is prepared from bisamino-terminated polydimethylsiloxane and resin A. The resin A is prepared by reacting an ester containing ring-opening maleic anhydride with styrene, butyl methacrylate and divinylbenzene. The ester containing ring-opening maleic anhydride is prepared by reacting 1,3-diglycidyl ether glycerol, triethylamine and chlorinated silica-grafted ring-opening maleic anhydride. The chlorinated silica-grafted ring-opening maleic anhydride is prepared by reacting silica-grafted ring-opening maleic anhydride with trimesoyl chloride. The silica-grafted ring-opening maleic anhydride is prepared by a ring-opening reaction between amino nano-silica and the anhydride group of maleic anhydride.

[0015] Preferably, the pigment is one or a combination of carbon black paste, iron red, toluidine red paste and phthalocyanine blue.

[0016] Preferably, the solvent is a mixture of one or more of xylene, toluene, ethylbenzene, cyclopentane, octane, heptane, cyclohexane, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, butyl acetate, propyl acetate, and benzyl acetate.

[0017] Preferably, the thickener is a mixture of one or more of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone.

[0018] Preferably, the plasticizer is one or a combination of dioctyl phthalate, diester phthalate, dioctyl adipate, octyl epoxy stearate, chlorinated paraffin, and triphenyl phosphate.

[0019] The preparation method of the antifouling and drag-reducing coating comprises the following steps:

[0020] S1: Aminated nano-silica undergoes a ring-opening reaction with the anhydride group of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; the silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100°C in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0021] S2: Add 1,3-diglycidyl ether glycerol and triethylamine to tetrahydrofuran solvent, add dropwise a tetrahydrofuran solution containing acyl chlorided silica grafted with ring-opened maleic anhydride in an ice-water bath under a nitrogen atmosphere, stir to carry out esterification reaction, filter, evaporate, wash, and vacuum dry to obtain an esterified product containing ring-opened maleic anhydride;

[0022] S3: Add the ester containing open-ring maleic anhydride, polyvinylpyrrolidone, azobisisobutyronitrile, and methanol to a three-necked flask under ultrasonic treatment and stir. During the stirring process, styrene, butyl methacrylate, and divinylbenzene are added to the above solution for reaction. The solution is centrifuged at a certain speed for a certain time, washed three times with ethanol, and dried at a certain temperature for a certain time to obtain resin A.

[0023] S4: Adding bisamino-terminated polydimethylsiloxane and ethanol solution to resin A, reacting for a period of time, washing with ethanol three times, and drying in an oven to obtain an antifouling resin.

[0024] S5: Weigh corresponding weights of antifouling resin, pigment, solvent, thickener, and plasticizer, and mechanically stir them until uniform, thereby obtaining an antifouling and drag-reducing coating.

[0025] Preferably, in step S1, the mass ratio of the amino-modified nano-silica to maleic anhydride is 1:1, and the mass ratio of the silica-grafted ring-opened maleic anhydride to trimesoyl chloride is 100:120.

[0026] Preferably, in step S2, the mass ratio of 1,3-diglycidyl ether glycerol, triethylamine and chlorinated silica grafted ring-opening maleic anhydride is 100:50-80:240-300.

[0027] Preferably, in step S3, the mass of the ester containing open-ring maleic anhydride is 1-2 g, the mass of polyvinyl pyrrolidone is 0.5-1 g, the mass of azobisisobutyronitrile is 0.15-0.2 g, 20-25 g of methanol are stirred for 30-40 minutes, 1-1.5 g of styrene, 0.4-0.6 g of butyl methacrylate, and 0.4-0.5 g of divinylbenzene are added to the above solution, reacted at 70-80 ° C for 6-8 hours, centrifuged at 4000-6000 rpm for 10-15 minutes, washed with ethanol three times, and dried at 50-60 ° C for 12-15 hours to obtain resin A.

[0028] Preferably, in step S4, the mass of bisamino-terminated polydimethylsiloxane is 10-15 g, the mass of the ethanol solution is 20-25 g, the mass of resin A is 25-30 g, the reaction time is 2-2.5 h, the oven temperature is 60-65° C., and the drying time is 5-8 min.

[0029] The beneficial effects of the present invention are:

[0030] (1) The antifouling and drag-reducing coating comprises amino-type nano-silica, which, under the nucleophilic action of amino groups, undergoes a ring-opening reaction with the anhydride group of maleic anhydride to obtain silica-grafted ring-opened maleic anhydride; the silica-grafted ring-opened maleic anhydride reacts with trimesoyl chloride to obtain chlorinated silica-grafted ring-opened maleic anhydride; the chlorinated silica-grafted ring-opened maleic anhydride, 1,3-diepoxyglycerol ether glycerol and triethylamine undergo an esterification reaction to obtain an ester containing ring-opened maleic anhydride. ; Add an ester containing open-ring maleic anhydride, polyvinyl pyrrolidone, azobisisobutyronitrile, and methanol to a three-necked flask under ultrasonic treatment and stir, and add styrene, butyl methacrylate, and divinylbenzene during the stirring process to react to obtain resin A; add bisaminopolydimethylsiloxane and ethanol solution to resin A to react to obtain an antifouling resin; weigh the corresponding weight of antifouling resin, pigment, solvent, thickener, and plasticizer, and stir them mechanically to obtain an antifouling and drag-reducing coating.

[0031] (2) In this antifouling and drag-reducing coating, the double bonds in the open-ring maleic anhydride react with the double bonds in the resin A to produce an Alder-ene reaction, thereby increasing the compatibility of silica in the coating. The open-ring maleic anhydride is used as a bridge to graft silica with 1,3-diepoxyglycerol ether glycerol. The epoxy groups in 1,3-diepoxyglycerol ether glycerol react with the hydroxyl groups on the hydroxylated substrate to produce a super-hydrophobic surface. The remaining epoxy groups can covalently react with bis-amino-terminated polydimethylsiloxane to graft a layer of coating on the super-hydrophobic surface. The grafted bis-amino-terminated polydimethylsiloxane has a low surface energy, which can improve the antifouling performance of the super-hydrophobic surface. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments. The following examples are intended to illustrate the present invention rather than to further limit the present invention. The technical means used in the following examples are conventional means well known to those skilled in the art, and all raw materials are general materials.

[0033] Example 1

[0034] The preparation method of antifouling resin, the specific preparation process is as follows:

[0035] S1: 100 g of amino-modified nano-silica undergoes a ring-opening reaction with the anhydride group of 100 g of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; 100 g of silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, 120 g of trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100° C. in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0036] S2: 100 g of 1,3-diglycidyl ether glycerol and 50 g of triethylamine were added to tetrahydrofuran solvent. In an ice-water bath and under a nitrogen atmosphere, 240 g of a tetrahydrofuran solution of chlorinated silica grafted with ring-opened maleic anhydride was added dropwise. The mixture was stirred for esterification reaction. The mixture was filtered, evaporated, washed, and dried under vacuum to obtain an esterified product containing ring-opened maleic anhydride.

[0037] S3: 1 g of ester containing open-ring maleic anhydride, 0.5 g of polyvinylpyrrolidone, 0.15 g of azobisisobutyronitrile, and 20 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 30 min. During the stirring process, 1 g of styrene, 0.4 g of butyl methacrylate, and 0.4 g of divinylbenzene were added to the above solution and reacted at 70°C for 6 h. The solution was centrifuged at 4000 rpm for 10 min, washed three times with ethanol, and dried at 50°C for 5 min to obtain resin A.

[0038] S4: 10 g of bisamino-terminated polydimethylsiloxane and 20 g of ethanol solution were added to 25 g of resin A. After reacting for 2 h, the mixture was washed with ethanol three times and dried in an oven at 60° C. for 5 min to obtain an antifouling resin.

[0039] S5: Weigh 30 g of antifouling resin, 10 g of carbon black slurry, 10 g of xylene, 5 g of sodium polyacrylate, and 5 g of dioctyl phthalate, and stir them mechanically to obtain an antifouling and drag-reducing coating.

[0040] Example 2

[0041] The preparation method of antifouling resin, the specific preparation process is as follows:

[0042] S1: 100 g of amino-modified nano-silica undergoes a ring-opening reaction with the anhydride group of 100 g of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; 100 g of silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, 120 g of trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100° C. in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0043] S2: 100 g of 1,3-diglycidyl ether glycerol and 60 g of triethylamine were added to tetrahydrofuran solvent. In an ice-water bath and under a nitrogen atmosphere, 250 g of a tetrahydrofuran solution of acyl chlorided silica grafted with ring-opened maleic anhydride was added dropwise. The mixture was stirred for esterification reaction. The mixture was filtered, evaporated, washed, and dried under vacuum to obtain an esterified product containing ring-opened maleic anhydride.

[0044] S3: 1.2 g of ester containing open-ring maleic anhydride, 0.6 g of polyvinylpyrrolidone, 0.16 g of azobisisobutyronitrile, and 21 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 32 minutes. During the stirring process, 1.1 g of styrene, 0.42 g of butyl methacrylate, and 0.42 g of divinylbenzene were added to the above solution for reaction. The reaction temperature was 72°C, the reaction time was 6.2 hours, and the mixture was centrifuged at 4500 rpm for 11 minutes. The mixture was washed three times with ethanol and dried at 52°C for 13 hours to obtain resin A.

[0045] S4: 11 g of bisamino-terminated polydimethylsiloxane and 21 g of ethanol solution were added to 26 g of resin A. After reacting for 2.1 h, the mixture was washed with ethanol three times and dried in an oven at 62° C. for 6 min to obtain an antifouling resin.

[0046] S5: Weigh 32 g of antifouling resin, 12 g of iron red, 12 g of toluene, 6 g of polyethylene oxide, and 6 g of phthalate diester, and mechanically stir them until uniform, thereby obtaining an antifouling and drag-reducing coating.

[0047] Example 3

[0048] The preparation method of antifouling resin, the specific preparation process is as follows:

[0049] S1: 100 g of amino-modified nano-silica undergoes a ring-opening reaction with the anhydride group of 100 g of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; 100 g of silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, 120 g of trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100° C. in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0050] S2: 100 g of 1,3-diglycidyl ether glycerol and 70 g of triethylamine were added to a tetrahydrofuran solvent. In an ice-water bath and under a nitrogen atmosphere, a tetrahydrofuran solution of 270 g of chlorinated silica grafted with ring-opened maleic anhydride was added dropwise. The mixture was stirred for esterification reaction. The mixture was filtered, evaporated, washed, and dried under vacuum to obtain an esterified product containing ring-opened maleic anhydride.

[0051] S3: 1.3 g of ester containing open-ring maleic anhydride, 0.7 g of polyvinylpyrrolidone, 0.17 g of azobisisobutyronitrile, and 22 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 33 minutes. During the stirring process, 1.2 g of styrene, 0.43 g of butyl methacrylate, and 0.43 g of divinylbenzene were added to the above solution for reaction. The reaction temperature was 73°C, the reaction time was 6.3 hours, and the mixture was centrifuged at 5000 rpm for 12 minutes. The mixture was washed three times with ethanol and dried at 53°C for 13.5 hours to obtain resin A.

[0052] S4: 12 g of bisamino-terminated polydimethylsiloxane and 22 g of ethanol solution were added to 27 g of resin A. After reacting for 2.2 h, the mixture was washed with ethanol three times and dried in an oven at 63° C. for 7 min to obtain an antifouling resin.

[0053] S5: Weigh 35 g of antifouling resin, 13 g of toluidine red slurry, 13 g of cyclopentane, 7 g of polyvinyl pyrrolidone, and 8 g of epoxy stearate, and stir them mechanically to obtain an antifouling and drag-reducing coating.

[0054] Example 4

[0055] The preparation method of antifouling resin, the specific preparation process is as follows:

[0056] S1: 100 g of amino-modified nano-silica undergoes a ring-opening reaction with the anhydride group of 100 g of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; 100 g of silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, 120 g of trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100° C. in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0057] S2: 100 g of 1,3-diglycidyl ether glycerol and 80 g of triethylamine were added to a tetrahydrofuran solvent. In an ice-water bath and under a nitrogen atmosphere, 300 g of a tetrahydrofuran solution of chlorinated silica grafted with ring-opened maleic anhydride was added dropwise. The mixture was stirred for esterification. The mixture was filtered, evaporated, washed, and dried under vacuum to obtain an esterified product containing ring-opened maleic anhydride.

[0058] S3: 1.5 g of an ester containing open-ring maleic anhydride, 0.8 g of polyvinylpyrrolidone, 0.18 g of azobisisobutyronitrile, and 25 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 35 minutes. During the stirring process, 1.5 g of styrene, 0.45 g of butyl methacrylate, and 0.45 g of divinylbenzene were added to the above solution for reaction. The reaction temperature was 80°C, the reaction time was 7 hours, and the mixture was centrifuged at 6000 rpm for 15 minutes. The mixture was washed three times with ethanol and dried at 55°C for 15 hours to obtain resin A.

[0059] S4: 15 g of bisamino-terminated polydimethylsiloxane and 25 g of ethanol solution were added to 30 g of resin A. After reacting for 2.5 h, the mixture was washed with ethanol three times and dried in an oven at 65° C. for 8 min to obtain an antifouling resin.

[0060] S5: Weigh 40 g of antifouling resin, 15 g of phthalocyanine blue, 15 g of octane, 8 g of polyvinyl pyrrolidone, and 9 g of chlorinated paraffin, and mechanically stir them until uniform, thereby obtaining an antifouling and drag-reducing coating.

[0061] Comparative Example 1

[0062] The preparation method of antifouling resin, the specific preparation process is as follows:

[0063] 1 g of silica, 0.5 g of polyvinylpyrrolidone, 0.15 g of azobisisobutyronitrile, and 20 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 30 minutes. During the stirring process, 1 g of styrene, 0.4 g of butyl methacrylate, and 0.4 g of divinylbenzene were added to the above solution for reaction. The reaction temperature was 70°C, the reaction time was 6 hours, and the mixture was centrifuged at 4000 rpm for 10 minutes, washed three times with ethanol, and dried at 50°C for 12 hours to obtain a mixture.

[0064] 10 g of bisamino-terminated polydimethylsiloxane and 20 g of ethanol solution were added to 25 g of the mixture prepared by (a3). After reacting for 2 h, the mixture was washed with ethanol three times and dried in an oven at 60°C for 5 min to obtain an antifouling resin.

[0065] 30 g of antifouling resin, 10 g of carbon black slurry, 10 g of xylene, 5 g of sodium polyacrylate, and 5 g of dioctyl phthalate were weighed and mechanically stirred to obtain an antifouling and drag-reducing coating.

[0066] Comparative Example 2

[0067] The preparation method of antifouling resin, the specific preparation process is as follows:

[0068] S1: 100 g of amino-modified nano-silica undergoes a ring-opening reaction with the anhydride group of 100 g of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; 100 g of silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, 120 g of trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100° C. in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride;

[0069] S2: 100 g of 1,3-diglycidyl ether glycerol and 50 g of triethylamine were added to tetrahydrofuran solvent. In an ice-water bath and under a nitrogen atmosphere, 240 g of a tetrahydrofuran solution of chlorinated silica grafted with ring-opened maleic anhydride was added dropwise. The mixture was stirred for esterification reaction. The mixture was filtered, evaporated, washed, and dried under vacuum to obtain an esterified product containing ring-opened maleic anhydride.

[0070] S3: 1 g of ester containing open-ring maleic anhydride, 0.5 g of polyvinylpyrrolidone, 0.15 g of azobisisobutyronitrile, and 20 g of methanol were added to a three-necked flask under ultrasonic treatment and stirred for 30 min. During the stirring process, 1 g of styrene, 0.4 g of butyl methacrylate, and 0.4 g of divinylbenzene were added to the above solution and reacted at 70°C for 6 h. The solution was centrifuged at 4000 rpm for 10 min, washed three times with ethanol, and dried at 50°C for 5 min to obtain resin A.

[0071] S4: Weigh 30 g of resin A, 10 g of carbon black slurry, 10 g of xylene, 5 g of sodium polyacrylate, and 5 g of dioctyl phthalate, and mechanically stir them until uniform, thereby obtaining an antifouling and drag-reducing coating.

[0072] The test methods and results of the drag reduction and antifouling performance of the antifouling and drag reducing coating prepared by the present invention are as follows:

[0073] Test Method: The coating was evenly applied to a test cylinder and subjected to a seawater scour test at 25°C. The cylinder speed was controlled, and the test was conducted over a 10-day cycle, with a 1:1 operating / rest ratio (one day of operation and one day of rest). After one test cycle, the cylinder specimen was removed and placed in a resistance test chamber for friction resistance testing. The test results are shown in Table 1 below.

[0074] Table 1

[0075]

[0076] Test panels coated with various antifouling coatings were subjected to dynamic testing at a depth of 6 meters. The panels were removed and observed at 40 and 100 days to assess their antifouling performance. The results are shown in Table 2.

[0077] Table 2

[0078]

[0079] Based on the data in Tables 1 and 2, it can be concluded that in Examples 1-4, increasing the amount of ring-opened maleic anhydride grafted onto acyl chloride silica results in a more uniform composition of the antifouling resin, increasing the amount of bis-amino-terminated polydimethylsiloxane, and increasing the amount of coating on the super-hydrophobic surface, leading to enhanced drag reduction and antifouling performance. In Comparative Example 1, silica easily agglomerates within the coating, resulting in poor drag reduction performance. In Comparative Example 2, where no bis-amino-terminated polydimethylsiloxane is introduced, the super-hydrophobic surface lacks a layer of coating, resulting in poor antifouling performance.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An antifouling and drag-reducing coating, characterized in that: It is prepared from the following raw materials in parts by weight: 30-40 parts of antifouling resin; 10~15 parts of pigment; 10-25 parts of solvent; 5-15 parts of thickener; 5-10 parts of plasticizer; The antifouling resin is prepared from bisamino-terminated polydimethylsiloxane and resin A. The resin A is prepared by reacting an ester containing ring-opening maleic anhydride with styrene, butyl methacrylate and divinylbenzene. The ester containing ring-opening maleic anhydride is prepared by reacting 1,3-diglycidyl ether glycerol, triethylamine and chlorinated silica-grafted ring-opening maleic anhydride. The chlorinated silica-grafted ring-opening maleic anhydride is prepared by reacting silica-grafted ring-opening maleic anhydride with trimesoyl chloride. The silica-grafted ring-opening maleic anhydride is prepared by a ring-opening reaction between amino nano-silica and the anhydride group of maleic anhydride.

2. The antifouling and drag-reducing coating according to claim 1, characterized in that: The pigment is one or a combination of carbon black paste, iron oxide red, toluidine red paste and phthalocyanine blue; the solvent is a mixture of one or more of xylene, toluene, ethylbenzene, cyclopentane, octane, heptane, cyclohexane, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, butyl acetate, propyl acetate and benzyl acetate; the thickener is a mixture of one or more of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone; and the plasticizer is one or a combination of dioctyl phthalate, diester phthalate, dioctyl adipate, octyl epoxy stearate, chlorinated paraffin and triphenyl phosphate.

3. The antifouling and drag-reducing coating according to claim 1, characterized in that: The preparation of resin A comprises the following steps: S1: Aminated nano-silica undergoes a ring-opening reaction with the anhydride group of maleic anhydride under the nucleophilic action of the amino group to obtain silica-grafted ring-opened maleic anhydride; the silica-grafted ring-opened maleic anhydride is added to anhydrous toluene solvent, and after ultrasonic dispersion, trimesoyl chloride is added, and the mixture is stirred at a constant temperature of 100°C in a nitrogen atmosphere for 10 hours. The product is centrifuged, washed, and dried to obtain chlorinated silica-grafted ring-opened maleic anhydride; S2: Add 1,3-diglycidyl ether glycerol and triethylamine to tetrahydrofuran solvent, add dropwise a tetrahydrofuran solution containing acyl chlorided silica grafted with ring-opened maleic anhydride in an ice-water bath under a nitrogen atmosphere, stir to carry out esterification reaction, filter, evaporate, wash, and vacuum dry to obtain an esterified product containing ring-opened maleic anhydride; S3: adding an ester containing ring-opened maleic anhydride, polyvinylpyrrolidone, azobisisobutyronitrile, and methanol to a three-necked flask under ultrasonic treatment and stirring; adding styrene, butyl methacrylate, and divinylbenzene to the solution during stirring to react; centrifuging at a certain speed for a certain time; washing with ethanol three times; and drying at a certain temperature for a certain time to obtain resin A; S4: adding bisamino-terminated polydimethylsiloxane and ethanol solution to resin A, reacting for a period of time, washing with ethanol three times, and drying in an oven to obtain an antifouling resin; S5: Weigh corresponding weights of antifouling resin, pigment, solvent, thickener, and plasticizer, and mechanically stir them until uniform, thereby obtaining an antifouling and drag-reducing coating.

4. The antifouling and drag-reducing coating according to claim 3, characterized in that: The mass ratio of the amino-treated nano-silica to maleic anhydride in step S1 is 1:1, and the mass ratio of the silica-grafted ring-opened maleic anhydride to trimesoyl chloride is 100:

120.

5. The antifouling and drag-reducing coating according to claim 3, characterized in that: In step S2, the mass ratio of 1,3-diglycidyl ether glycerol, triethylamine and chlorinated silicon dioxide grafted ring-opening maleic anhydride is 100:50-80:240-300.

6. The antifouling and drag-reducing coating according to claim 3, characterized in that: In step S3 The mass of the ester containing open-ring maleic anhydride is 1-2 g, the mass of polyvinylpyrrolidone is 0.5-1 g, the mass of azobisisobutyronitrile is 0.15-0.2 g, and 20-25 g of methanol are stirred for 30-40 minutes. 1-1.5 g of styrene, 0.4-0.6 g of butyl methacrylate, and 0.4-0.5 g of divinylbenzene are added to the above solution, and the reaction is carried out at 70-80°C for 6-8 hours. The mixture is centrifuged at a speed of 4000-6000 rpm for 10-15 minutes, washed with ethanol three times, and dried at 50-60°C for 12-15 hours to obtain resin A.

7. The antifouling and drag-reducing coating according to claim 3, characterized in that: In step S4 The mass of bisamino-terminated polydimethylsiloxane is 10-15 g, the mass of the ethanol solution is 20-25 g, the mass of resin A is 25-30 g, the reaction time is 2-2.5 h, the oven temperature is 60-65 ° C, and the drying time is 5-8 min.

Images