An antioxidant coating and a method for preparing the same

Abstract

The application discloses an antioxidant coating and a preparation method thereof, and relates to the technical field of coatings. The application first uses hydroxybenzotriazole to esterify and modify acrylic acid, and then uses the modified acrylic acid to prepare modified acrylic resin coating. The benzotriazole structure has high hardness and rigidity, and also has good ultraviolet absorption performance, which can reduce the degradation of the acrylic resin caused by ultraviolet rays and further improve the durability of the coating. The microcapsule wall material is modified by a hydrophobic compound, and then a new type of microcapsule wall material is prepared by coating an antioxidant. The microcapsule wall material modified by the hydrophobic compound can effectively prevent external moisture and oxygen from entering the microcapsule, improve the stability of the coating in a humid environment, and protect the antioxidant in the core material from the influence of the external environment. The antioxidant is slowly and continuously released in the coating, and the oxidation reaction of the coating is effectively inhibited for a long time. The antioxidant coating prepared by the application has the effects of wear resistance and durability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to an antioxidant coating and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of industrial technology, the oxidation problem of materials in harsh environments such as high temperature and high humidity is increasingly prominent, which seriously affects the service life and performance stability of the materials. The research and development of antioxidant coatings has become a key direction to solve this problem. Traditional coatings have obvious shortcomings in high temperature resistance and oxidation resistance, especially in the fields of aerospace, energy, automobile, etc., materials need to operate stably for a long time under extreme conditions, so it is urgent to develop new antioxidant coatings.

[0003] Therefore, it is of important scientific research value and practical application significance to develop new coatings with high efficient antioxidant performance, environmental friendliness and economic efficiency. SUMMARY

[0004] The purpose of the present application is to provide an antioxidant coating and a preparation method thereof to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: an antioxidant coating is prepared from the following components by weight fraction:

[0006] 40-60 parts of modified acrylic resin, 1-3 parts of dispersant, 5-10 parts of thickening agent, 3-5 parts of film forming aid, 0.5-1 part of defoaming agent, 1-3 parts of new type microcapsule antioxidant, 10-15 parts of filler, 30-45 parts of deionized water;

[0007] The modified acrylic resin is prepared from 1-hydroxybenzotriazole modified acrylic ester, and then polymerized with acrylic ester and its derivatives;

[0008] The new type microcapsule antioxidant is prepared by modifying the microcapsule wall material with a hydrophobic compound, and then coating the antioxidant.

[0009] Further, the dispersant is one of sodium oleate, sodium acetate, sodium sulfate ester and sodium dodecyl sulfonate; the thickening agent is a polyurethane thickening agent.

[0010] Further, the film forming aid is an alcohol ester film forming aid; the defoaming agent is polysiloxane, and the filler is one or more of silicon dioxide, barium sulfate and calcium sulfate.

[0011] Further, the hydrophobic compound is one of cinnamic acid, benzoic acid and its derivatives, or naphthoic acid and its derivatives.

[0012] Further, the microcapsule wall material is one of gelatin, sodium alginate, gum arabic or chitosan, and the antioxidant is an oil-phase antioxidant.

[0013] Further, a preparation method of the antioxidant coating comprises the following preparation steps:

[0014] (1) grafting a hydrophobic compound to a microcapsule wall material to obtain a modified wall material, dissolving the modified wall material in a 1wt% acetic acid solution to prepare a 1wt% modified wall material solution, adding an oil-phase antioxidant in an amount of 0.6-0.8 times the mass of the modified wall material to obtain a core mixture, adding an emulsifier in an amount of 0.0045-0.0060 times the mass of the core mixture, stirring at 12000-13000 rpm for 10-15 min, homogenizing, and spray drying to obtain a novel microcapsule antioxidant;

[0015] (2) mixing 1-hydroxybenzotriazole and dimethyl sulfoxide in a mass ratio of 1:3-5, adding acrylic acid in an amount of 1.2-1.5 times the mass of the hydroxybenzotriazole, stirring at 300-400 r / min for 10-15 min to obtain a mixture, adding p-toluenesulfonic acid in an amount of 0.05-0.1 times the mass of the mixture, reacting at 78-79℃ and 100-150 r / min for 6-8 h, extracting, and removing the solvent by reduced pressure distillation to obtain a modified acrylic ester;

[0016] (3) mixing the acrylic ester and derivatives thereof and the modified acrylic ester in a mass ratio of 5.3-7.6:1 to obtain a prepolymer solution, dissolving the prepolymer solution in butanone in an amount of 2-3 times the mass of the prepolymer solution, adding an initiator in an amount of 0.3-0.4 times the mass of the prepolymer solution, stirring at 400-500 r / min for 20-30 min, reacting at 80-140℃ for 3-4 h, and naturally cooling to obtain a modified acrylic resin;

[0017] (4) mixing by weight parts, mixing the modified acrylic resin 40-60 parts, a dispersing agent 1-3 parts, a thickening agent 5-10 parts, a film-forming aid 3-5 parts, an antifoaming agent 0.5-1 part, the novel microcapsule antioxidant 1-3 parts, a filler 10-15 parts, and deionized water 30-45 parts, stirring, filtering, and defoaming to obtain the antioxidant coating.

[0018] Further, the spray drying in step (1) is performed under the following conditions: an inlet air temperature of 180℃ and an outlet air temperature of 80-85℃.

[0019] Further, the emulsifier in step (1) is Tween 80.

[0020] Further, the homogenization in step (1) is performed at 35 MPa for 10-15 min.

[0021] Further, the initiator in step (3) is benzoyl peroxide.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] The present application prepares a modified acrylic resin by esterification modification of acrylic acid with hydroxy benzotriazole, and then adds a new type of microcapsule antioxidant to prepare an antioxidant coating, so as to achieve the effects of wear resistance and durability.

[0024] Firstly, the hydroxy benzotriazole is esterified and modified to prepare a modified acrylic resin coating; the benzotriazole structure has high hardness and rigidity, and the benzotriazole structure is introduced into the acrylic resin through esterification reaction, so that the acrylic resin is more wear-resistant, the surface wear caused by friction is reduced, the service life of the coating is prolonged, and the coating has good ultraviolet absorption performance, can convert ultraviolet rays into harmless heat energy, thereby reducing the degradation of the acrylic resin by ultraviolet rays, further improving the durability of the coating, and the benzotriazole group is chemically bonded to the resin main chain, avoiding the migration and volatilization problems of traditional additive ultraviolet absorbers.

[0025] Secondly, the microcapsule wall material is modified with a hydrophobic compound, and then the antioxidant is coated to prepare a new type of microcapsule wall material; the microcapsule wall material modified by the hydrophobic compound can effectively prevent external water and oxygen from entering the microcapsule, thereby reducing the contact opportunity of the antioxidant with water and oxygen, reducing the possibility of oxidation, improving the storage stability and use effect of the antioxidant, improving the stability of the coating in a humid environment, and the coating of the microcapsule protects the core material antioxidant from the influence of the external environment, slowly and continuously releases the antioxidant in the coating, long-term effectively inhibits the oxidation reaction of the coating, prevents the antioxidant from failing prematurely during storage and use, and improves the stability and durability of the coating. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] In order to more clearly illustrate the method provided by the present application, the following examples are used for detailed description, and the test methods of various indexes of an antioxidant coating prepared in the following examples are as follows:

[0028] Antioxidant performance: the same mass of the antioxidant coatings prepared in the examples and the comparative examples is poured into a mold, and an antioxidant coating film is obtained by solidification, and the antioxidant performance is tested according to GB / T 1865-2009 "Paints and Varnishes Artificial Weathering and Artificial Radiation Exposure".

[0029] Abrasion resistance: antioxidant coatings prepared from the same mass of examples and comparative examples were poured into a mold, and antioxidant coating films were obtained by curing. The films were tested for abrasion resistance according to GB / T 23988-2009 "Determination of Abrasion Resistance of Coatings - Falling Sand Method".

[0030] Durability: antioxidant coatings prepared from the same mass of examples and comparative examples were poured into a mold, and antioxidant coating films were obtained by curing. The films were subjected to 16 hours of high-temperature sweat corrosion, 6 hours of strong acid corrosion, 12 hours of strong base corrosion, and 100 hours of high-intensity ultraviolet radiation. The surface of the samples was observed to determine whether there were any cracks or peeling.

[0031] Example 1

[0032] A method for preparing an antioxidant coating, comprising the following preparation steps:

[0033] (1) Cinnamic acid, chitosan, and 60 wt% sulfuric acid were mixed in a mass ratio of 1:1.1:0.4, dissolved in anhydrous ethanol in an amount of 1.5 times the mass of the mixture, stirred at 400 r / min under a nitrogen atmosphere for 5 h in a 60°C oil bath, cooled to room temperature, and then rotary evaporated to remove the solvent, thereby obtaining a modified wall material;

[0034] (2) The modified wall material was dissolved in a 1 wt% acetic acid solution to prepare a 1 wt% modified wall material solution. BHT was added in an amount of 0.7 times the mass of the modified wall material to obtain a wall core mixture. Tween 80 was added in an amount of 0.005 times the mass of the wall core mixture. The mixture was stirred at 12000 rpm for 10 min, homogenized at 35 MPa for 12 min, and spray dried at an inlet temperature of 180°C and an outlet temperature of 80°C to obtain a new type of microcapsulated antioxidant;

[0035] (3) 1-hydroxybenzotriazole and dimethyl sulfoxide were mixed in a mass ratio of 1:4. Acrylic acid was added in an amount of 1.3 times the mass of the hydroxybenzotriazole. The mixture was stirred at 400 r / min for 15 min. p-toluenesulfonic acid was added in an amount of 0.05 times the mass of the mixture. The reaction was carried out at 78°C and 100 r / min for 6 h. The product was extracted and then distilled under reduced pressure to remove the solvent, thereby obtaining a modified acrylic ester;

[0036] (4) The acrylic ester and its derivatives were mixed with the modified acrylic ester in a mass ratio of 5.3:1 to obtain a prepolymer solution. The acrylic ester included methyl methacrylate, methyl methacrylate, and acrylic acid in a mass ratio of 2:1:0.3. The prepolymer solution was dissolved in butanone in an amount of 2-3 times the mass of the prepolymer solution. Benzyol peroxide was added in an amount of 0.3-0.4 times the mass of the prepolymer solution. The mixture was stirred at 400-500 r / min for 20-30 min and reacted at 80-140°C for 3-4 h. The product was naturally cooled to obtain a modified acrylic resin;

[0037] (5) mixing by weight, mixing modified acrylic resin 40 parts, sodium dodecyl sulfonate 1 part, HEUR polyurethane thickening agent 5 parts, dodecanol ester YT-12 film forming aid 3 parts, polysiloxane 0.5 parts, new microcapsule antioxidant 1 part, silicon dioxide 10 parts, deionized water 30 parts, stirring, filtering, defoaming to obtain antioxidant coating.

[0038] Example 2

[0039] A preparation method of an antioxidant coating, comprising the following preparation steps:

[0040] (1) mixing cinnamic acid, sodium alginate and 60wt% sulfuric acid in a mass ratio of 1:1.1:0.4, dissolving in anhydrous ethanol with a mass of 1.5 times of the mixed solution, stirring at 400r / min under nitrogen atmosphere for 5h at 65℃ oil bath, cooling to room temperature, and then removing the solvent by rotary evaporation to obtain a modified wall material;

[0041] (2) dissolving the modified wall material in 1wt% acetic acid solution to prepare a 1wt% modified wall material solution, adding BHT with a mass of 0.6 times of the modified wall material to obtain a core mixture, adding Tween 80 with a mass of 0.0045 times of the core mixture, stirring at 12000rpm for 10min, homogenizing at 35MPa for 10min, and spray drying under the conditions of inlet air temperature of 180℃ and outlet air temperature of 80℃ to obtain a new microcapsule antioxidant;

[0042] (3) mixing 1-hydroxybenzotriazole and dimethyl sulfoxide in a mass ratio of 1:3~5, adding acrylic acid with a mass of 1.5 times of the hydroxybenzotriazole, stirring at 400r / min for 10~15min to obtain a mixture, adding p-toluenesulfonic acid with a mass of 0.05 times of the mixture, reacting at 79℃ and 150r / min for 8h, extracting, and then removing the solvent by reduced pressure distillation to obtain a modified acrylic ester;

[0043] (4) mixing the acrylic ester and its derivatives with the modified acrylic ester in a mass ratio of 5.3:1 to obtain a prepolymer solution, wherein the acrylic ester includes methyl methacrylate, methyl methacrylate and acrylic acid in a mass ratio of 2:1:0.3, dissolving in butanone with a mass of 2 times of the prepolymer solution, adding benzoyl peroxide with a mass of 0.3 times of the prepolymer solution, stirring at 500r / min for 20min, and reacting at 90℃ for 4h to obtain a modified acrylic resin;

[0044] (5) mixing by weight, mixing modified acrylic resin 50 parts, sodium dodecyl sulfonate 1 part, HEUR polyurethane thickening agent 5 parts, dodecanol ester YT-12 film forming aid 3 parts, polysiloxane 0.5 parts, new microcapsule antioxidant 1 part, silicon dioxide 10 parts, deionized water 30 parts, stirring, filtering, defoaming to obtain antioxidant coating.

[0045] Example 3

[0046] A preparation method of an antioxidant coating, comprising the following preparation steps:

[0047] (1) mixing benzoic acid, chitosan and 60wt% sulfuric acid in a mass ratio of 1:1.1:0.4, dissolving in anhydrous ethanol with a mass of 1.5 times of the mixed solution, stirring at 400r / min under nitrogen atmosphere for 6h in a 60℃ oil bath, cooling to room temperature, and then removing the solvent by rotary evaporation to obtain a modified wall material;

[0048] (2) dissolving the modified wall material in a 1wt% acetic acid solution to prepare a 1wt% modified wall material solution, adding BHT with a mass of 0.7 times of the modified wall material to obtain a core-shell mixture, adding Tween 80 with a mass of 0.0060 times of the core-shell mixture, stirring at 13000rpm for 15min, homogenizing at 35MPa for 15min, and spray drying under the conditions of an inlet air temperature of 180℃ and an outlet air temperature of 85℃ to obtain a novel microcapsulated antioxidant;

[0049] (3) mixing 1-hydroxybenzotriazole and dimethyl sulfoxide in a mass ratio of 1:4, adding acrylic acid with a mass of 1.3 times of the hydroxybenzotriazole, stirring at 400r / min for 15min to obtain a mixture, adding p-toluenesulfonic acid with a mass of 0.05 times of the mixture, reacting at 79℃ and 150r / min for 6h, extracting, and then removing the solvent by reduced pressure distillation to obtain a modified acrylic ester;

[0050] (4) mixing the acrylic ester and its derivatives and the modified acrylic ester in a mass ratio of 7.6:1 to obtain a prepolymer solution, wherein the acrylic ester includes methyl methacrylate, methyl methacrylate and acrylic acid in a mass ratio of 5:2:0.6, dissolving in butanone with a mass of 2 times of the prepolymer solution, adding benzoyl peroxide with a mass of 0.3 times of the prepolymer solution, stirring at 400r / min for 25min, and reacting at 110℃ for 3h to obtain a modified acrylic resin;

[0051] (5) mixing, by weight parts, the modified acrylic resin 50 parts, sodium dodecyl sulfonate 2 parts, HEUR polyurethane thickener 7 parts, dodecanol ester YT-12 film-forming aid 4 parts, polysiloxane 0.6 parts, novel microcapsulated antioxidant 2 parts, silicon dioxide 13 parts, and deionized water 35 parts, stirring, filtering, and defoaming to obtain the antioxidant coating.

[0052] Example 4

[0053] A preparation method of an antioxidant coating, comprising the following preparation steps:

[0054] (1) mixed naphthoic acid, chitosan, 60wt% sulfuric acid in a mass ratio of 1:1.1:0.4, dissolved in anhydrous ethanol with 1.5 times the mass of the mixed solution, stirred at 60°C oil bath under nitrogen atmosphere at 450r / min for 6h, cooled to room temperature, and then removed the solvent by rotary evaporation to obtain a modified wall material;

[0055] (2) the modified wall material was dissolved in 1wt% acetic acid solution to prepare a 1wt% modified wall material solution, and then BHT was added to the wall core mixture with a mass of 0.7 times the mass of the modified wall material, and Tween 80 was added to the wall core mixture with a mass of 0.0055 times the mass of the wall core mixture, stirred at 13000rpm for 12min, homogenized at 35MPa for 13min, and spray dried at an inlet air temperature of 180°C and an outlet air temperature of 85°C to obtain a new type of microcapsulated antioxidant;

[0056] (3) mixed 1-hydroxybenzotriazole and dimethyl sulfoxide in a mass ratio of 1:45, added acrylic acid with a mass of 1.3 times the mass of hydroxybenzotriazole, stirred at 350r / min for 13min to obtain a mixture, added p-toluenesulfonic acid with a mass of 0.07 times the mass of the mixture, reacted at 79°C and 130r / min for 7h, extracted, and then removed the solvent by reduced pressure distillation to obtain a modified acrylic ester;

[0057] (4) mixed the acrylic ester and its derivatives with the modified acrylic ester in a mass ratio of 6.5:1 to obtain a prepolymer solution, wherein the acrylic ester includes methyl methacrylate, methyl methacrylate, and acrylic acid in a mass ratio of 4:1.1:0.4, dissolved in butanone with a mass of 2 times the mass of the prepolymer solution, added benzoyl peroxide with a mass of 0.3 times the mass of the prepolymer solution, stirred at 450r / min for 25min, reacted at 100°C for 3h, and then naturally cooled to obtain a modified acrylic resin;

[0058] (5) mixed, according to weight parts, the modified acrylic resin 50 parts, sodium dodecyl sulfonate 2 parts, HEUR polyurethane thickener 7 parts, dodecanol ester YT-12 film forming aid 4 parts, polysiloxane 0.6 parts, new type of microcapsulated antioxidant 2 parts, silicon dioxide 13 parts, and deionized water 35 parts, stirred, filtered, and defoamed to obtain an antioxidant coating.

[0059] Example 5

[0060] A preparation method of an antioxidant coating, comprising the following preparation steps:

[0061] (1) mixed naphthoic acid, chitosan, 60wt% sulfuric acid in a mass ratio of 1:1.1:0.4, dissolved in anhydrous ethanol with 1.5 times the mass of the mixed solution, stirred at 60°C oil bath under nitrogen atmosphere at 400r / min for 6h, cooled to room temperature, and then removed the solvent by rotary evaporation to obtain a modified wall material;

[0062] (2) The modified wall material is dissolved in 1wt% acetic acid solution to form a 1wt% modified wall material solution. The wall core mixture is prepared by adding 0.7 times the mass of BHT to the modified wall material. The wall core mixture is prepared by adding 0.0045 times the mass of Tween 80. The mixture is stirred at 12000 rpm for 13 min, homogenized at 35 MPa for 13 min, and spray dried at an inlet temperature of 180°C and an outlet temperature of 80°C to obtain a new type of microcapsulated antioxidant.

[0063] (3) 1-hydroxybenzotriazole and dimethyl sulfoxide are mixed in a mass ratio of 1:4. Acrylic acid is added in an amount of 1.3 times the mass of hydroxybenzotriazole. The mixture is stirred at 350 r / min for 13 min. p-toluenesulfonic acid is added in an amount of 0.07 times the mass of the mixture. The reaction is carried out at 78°C and 130 r / min for 7 h. The solvent is removed by extraction and reduced pressure distillation to obtain a modified acrylic ester.

[0064] (4) The acrylic ester and its derivatives are mixed with the modified acrylic ester in a mass ratio of 7.6:1 to obtain a prepolymer solution. The acrylic ester includes methyl methacrylate, methyl methacrylate, and acrylic acid in a mass ratio of 5:2:0.6. The prepolymer solution is dissolved in 2 times the mass of butanone. Benzoyl peroxide is added in an amount of 0.3 times the mass of the prepolymer. The mixture is stirred at 450 r / min for 25 min and reacted at 100°C for 4 h. The modified acrylic resin is obtained by natural cooling.

[0065] (5) The modified acrylic resin, sodium dodecyl sulfonate, HEUR polyurethane thickener, dodecanol ester YT-12 film-forming aid, polysiloxane, new type of microcapsulated antioxidant, silicon dioxide, and deionized water are mixed in a weight ratio of 55:2:8:4:0.8:2:13:35. After stirring, filtering, and degassing, the antioxidant coating is obtained.

[0066] Comparative Example 1

[0067] The difference between Comparative Example 1 and Example 2 is that step (3) is different. In step (3), 1-hydroxybenzotriazole is replaced by ethanol. The remaining steps are the same as Example 2.

[0068] Comparative Example 2

[0069] The difference between Comparative Example 2 and Example 2 is that there is no step (3). In step (4), the modified acrylic ester is replaced by n-butyl methacrylate. The remaining steps are the same as Example 2.

[0070] Comparative Example 3

[0071] The difference between Comparative Example 3 and Example 2 is that there is no step (1). In step (2), the modified wall material is replaced by sodium alginate. The remaining steps are the same as Example 2.

[0072] Comparative Example 4

[0073] Comparative Example 4 differs from Example 2 in that steps (1) and (2) are not performed, and the novel microcapsule antioxidant in step (5) is replaced by BHT; the remaining steps are the same as in Example 2.

[0074] Effect Example

[0075] The performance analysis results of the antioxidant coatings using Examples 1-5 and Comparative Examples 1-4 of the present application are shown in Table 1 below.

[0076]

[0077] From the comparison of the experimental data of Example 2 and Comparative Examples 1 and 2, it can be found that the present application uses hydroxybenzotriazole esterification to modify acrylic acid, and then uses the modified acrylic acid to prepare a modified acrylic resin coating. The benzotriazole structure has high hardness and rigidity, and by introducing the benzotriazole structure into the acrylic resin through esterification, the wear resistance of the acrylic resin is improved, the surface wear caused by friction is reduced, the service life of the coating is prolonged, and the coating has good ultraviolet absorption performance, which can convert ultraviolet rays into harmless heat energy, thereby reducing the degradation of the acrylic resin by ultraviolet rays and further improving the durability of the coating. From the comparison of the experimental data of Example 2 and Comparative Examples 3 and 4, it can be found that the present application further uses a hydrophobic compound to modify the microcapsule wall material, and then coats an antioxidant to prepare a novel microcapsule wall material. The microcapsule wall material modified by the hydrophobic compound can effectively prevent external moisture and oxygen from entering the inside of the microcapsule, thereby reducing the contact opportunities of the antioxidant with moisture and oxygen, reducing the possibility of oxidation, improving the storage stability and use effect of the antioxidant, improving the stability of the coating in a humid environment, and the coating of the microcapsule protects the antioxidant core material from the influence of the external environment, slowly and continuously releases the antioxidant in the coating, long-term effectively inhibits the oxidation reaction of the coating, prevents the antioxidant from prematurely failing during storage and use, and improves the stability and durability of the coating.

[0078] It will be apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the elements of the claims. Any mark in the claims should not be considered as limiting the involved claims.

Claims

1. An antioxidant coating, characterized in that, It is made from the following components in parts by weight: 40-60 parts modified acrylic resin, 1-3 parts dispersant, 5-10 parts thickener, 3-5 parts film-forming aid, 0.5-1 part defoamer, 1-3 parts novel microcapsule antioxidant, 10-15 parts filler, and 30-45 parts deionized water; The modified acrylic resin is prepared by modifying acrylate with 1-hydroxybenzotriazole and then polymerizing it with acrylate and its derivatives. The novel microcapsule antioxidant is prepared by modifying the microcapsule wall material with a hydrophobic compound and then coating it with an antioxidant.

2. The antioxidant coating according to claim 1, characterized in that, The dispersant is one of sodium oleate, sodium acetate, sodium sulfate, and sodium dodecyl sulfonate; the thickener is a polyurethane thickener.

3. The antioxidant coating according to claim 2, characterized in that, The film-forming aid is an alcohol ester film-forming aid; the defoamer is a polysiloxane; and the filler is one or more of silicon dioxide, barium sulfate, and calcium sulfate.

4. The antioxidant coating according to claim 1, characterized in that, The hydrophobic compound is one of cinnamic acid, benzoic acid and its derivatives, or naphthoic acid and its derivatives.

5. The antioxidant coating according to claim 1, characterized in that, The microcapsule wall material is one of gelatin, sodium alginate, gum arabic, or chitosan, and the antioxidant is an oil-phase antioxidant.

6. A method for preparing an antioxidant coating, characterized in that, The preparation steps include the following: (1) A modified wall material is obtained by grafting a hydrophobic compound onto the wall material of a microcapsule. The modified wall material is dissolved in a 1 wt% acetic acid solution to prepare a 1 wt% modified wall material solution. An oil phase antioxidant of 0.6 to 0.8 times the mass of the modified wall material is added to obtain a wall core mixture. An emulsifier of 0.0045 to 0.0060 times the mass of the wall core mixture is added. The mixture is stirred at 12000 to 13000 rpm for 10 to 15 min, homogenized, and spray-dried to obtain a novel microcapsule antioxidant. (2) Mix 1-hydroxybenzotriazole and dimethyl sulfoxide in a mass ratio of 1:3~5, add acrylic acid of 1.2~1.5 times the mass of hydroxybenzotriazole, stir at 300~400 r / min for 10~15 min to obtain a mixture, add p-toluenesulfonic acid of 0.05~0.1 times the mass of the mixture, react at 78~79℃ and 100~150 r / min for 6~8 h, extract, and then remove the solvent by vacuum distillation to obtain modified acrylate; (3) Mix acrylate and its derivatives with modified acrylate at a mass ratio of 5.3~7.6:1 to obtain a prepolymer solution, dissolve it in 2~3 times the mass of methyl ethyl ketone, add 0.3~0.4 times the mass of the prepolymer solution as an initiator, stir at 400~500 r / min for 20~30 min, react at 80~140℃ for 3~4 h, and cool naturally to obtain modified acrylic resin; (4) Mix by weight: 40-60 parts of modified acrylic resin, 1-3 parts of dispersant, 5-10 parts of thickener, 3-5 parts of film-forming aid, 0.5-1 part of defoamer, 1-3 parts of novel microcapsule antioxidant, 10-15 parts of filler, and 30-45 parts of deionized water. Stir, filter, and degas to obtain antioxidant coating.

7. The method for preparing an antioxidant coating according to claim 6, characterized in that, The conditions for spray drying in step (1) are: inlet air temperature 180℃ and outlet air temperature 80~85℃.

8. The method for preparing an antioxidant coating according to claim 6, characterized in that, The emulsifier in step (1) is Tween 80.

9. The method for preparing an antioxidant coating according to claim 6, characterized in that, In step (1), homogenization is performed at 35 MPa for 10-15 minutes.

10. The method for preparing an antioxidant coating according to claim 6, characterized in that, The initiator in step (3) is benzoyl peroxide.

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