Environment-friendly six-proofing paint and preparation method thereof

Abstract

The invention discloses environment-friendly six-proofing paint and a preparation method thereof, and belongs to the technical field of paints.The environment-friendly six-proofing paint is prepared from, by weight, 30-50 parts of epoxy resin, 10-20 parts of modified polyurethane, 3-5 parts of dispersing agent, 1-2 parts of mildew preventive, 1-2 parts of flatting agent, 1-2 parts of anti-settling agent, 10-20 parts of modified filler, 1-2 parts of anti-freezing agent, 3-5 parts of curing agent and 5-10 parts of acetone. The waterborne epoxy resin and the modified polyurethane are used as main film forming substances, acetone is used as a solvent, VOC emission can be effectively reduced, VOC emission is extremely low, and the environment-friendly requirement is met; a flexible siloxane section of a polyurethane molecular chain is complementary with a rigid structure of epoxy resin, so that cracking and peeling phenomena caused by thermal expansion and cold contraction or external force can be effectively resisted, and the durability and reliability of the coating are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to an environmentally friendly six-proof paint and a preparation method thereof. Background Art

[0002] With the accelerating pace of industrialization and urbanization, metal materials and electronic devices are increasingly used in various complex environments, placing higher demands on the performance of their surface protective coatings. Traditional protective coatings, which primarily use epoxy resins and polyurethanes as film-forming materials, can provide substrates with multiple protections, including corrosion resistance, mildew resistance, and wear resistance. However, existing coating materials still commonly suffer from the following deficiencies: On the one hand, many traditional anti-corrosion coatings use large amounts of organic solvents during their preparation and application, resulting in high VOC (volatile organic compound) emissions. This not only affects human health but also pollutes the environment, making it difficult to meet the requirements of green and environmentally friendly processes. On the other hand, single resin systems, such as traditional epoxy resin coatings, while structurally stable and corrosion-resistant, are also relatively rigid and prone to cracking due to thermal expansion and contraction or mechanical impact, which in turn reduces the coating's durability and adhesion. While conventional polyurethane coatings offer good flexibility and water resistance, their chemical and high-temperature resistance lags behind epoxy resin systems.

[0003] Typically, integrating multiple properties, such as wear resistance, adhesion, corrosion resistance, antibacterial properties, impact resistance, and water resistance, often creates constraints. For example, pursuing high adhesion and corrosion resistance can easily compromise the material's flexibility and impact resistance, while improving water resistance can lead to a decrease in the coating's interfacial bonding properties. Therefore, it is necessary to develop an environmentally friendly, low-VOC, conformal coating that simultaneously delivers multiple protective properties, including wear resistance, adhesion, corrosion resistance, antibacterial properties, impact resistance, and water resistance. Summary of the Invention

[0004] The main purpose of the present invention is to provide an environmentally friendly six-proof paint and a preparation method thereof. The environmentally friendly six-proof paint prepared by the present invention has good wear resistance, adhesion, corrosion resistance, antibacterial, impact resistance and water resistance.

[0005] To achieve the above objectives, the present invention proposes an environmentally friendly six-proof paint, comprising the following components by weight: 30-50 parts of epoxy resin, 10-20 parts of modified polyurethane, 3-5 parts of dispersant, 1-2 parts of mildewcide, 1-2 parts of leveling agent, 1-2 parts of anti-settling agent, 10-20 parts of modified filler, 1-2 parts of antifreeze agent, 3-5 parts of curing agent, and 5-10 parts of acetone.

[0006] Preferably, the preparation method of the modified polyurethane is as follows: (1) Add dimethylhydroxy silicone oil and stannous octoate into a reaction vessel and stir evenly, then add hexamethylene diisocyanate and heat to react to obtain silicone oil modified polyurethane; (2) Ethyl 4-aminocinnamate is added to the silicone oil modified polyurethane, stirred, and then 2,6-di-tert-butyl-p-cresol is added, stirred and reacted for a period of time, and then 2-hydroxyethyl methacrylate phosphate and an initiator are added, and heated to react to obtain the modified polyurethane.

[0007] Preferably, in step (1), the mass ratio of the dimethylhydroxy silicone oil, stannous octoate, and hexamethylene diisocyanate is 18-20:0.05-0.1:3-5.

[0008] Preferably, in step (2), the mass ratio of ethyl 4-aminocinnamate, silicone oil-modified polyurethane, 2,6-di-tert-butyl-p-cresol, 2-hydroxyethyl methacrylate phosphate, and initiator is 2-5:10-15:0.01-0.1:1-3:0.01-0.05.

[0009] Preferably, in step (1), the temperature of the temperature-raising reaction is 50-80°C and the time is 2-4 hours; in step (2), the temperature of the stirring reaction is 50-70°C and the time is 4-6 hours; and the temperature of the heating reaction is 60-80°C and the reaction time is 2-4 hours.

[0010] The modified polyurethane of the invention is prepared by reacting dimethylhydroxy silicone oil with hexamethylene diisocyanate under the action of stannous octoate to obtain silicone oil-modified polyurethane, then introducing 2-aminoethyl methacrylate containing a carbon-carbon double bond into the molecular structure of the modified polyurethane using 2,6-di-tert-butyl-p-cresol as a polymerization inhibitor, and finally reacting with 2-hydroxyethyl methacrylate phosphate under the action of an initiator to obtain the obtained polyurethane.

[0011] Preferably, the preparation method of the modified filler is as follows: The carbon nanotubes are dispersed in concentrated sulfuric acid and subjected to ultrasonic heating treatment to obtain pretreated carbon nanotubes. The pretreated carbon nanotubes are dispersed in an ethanol aqueous solution, a vinyl silane coupling agent is added, and the mixture is heated to react to obtain activated carbon nanotubes. Heptadecenylaminoethylimidazoline quaternary ammonium salt is dissolved in toluene, and the activated carbon nanotubes and ammonium persulfate are added in sequence and heated to react to obtain the modified filler.

[0012] Further preferably, the mass ratio of the pretreated carbon nanotubes, the vinyl silane coupling agent, and the heptadecenylamine ethyl imidazoline quaternary ammonium salt is 20-30:3-5:5-8.

[0013] Preferably, the dispersant is at least one of sodium polyacrylate, trisodium phosphate, alkylphenol polyoxyethylene ether, and sodium alkyl aryl sulfonate.

[0014] Preferably, the antifungal agent is chitosan.

[0015] Preferably, the leveling agent is BYK-111.

[0016] Preferably, the anti-settling agent is fumed silica.

[0017] Preferably, the antifreeze agent is tristyrylphenol polyoxyethylene ether.

[0018] Preferably, the curing agent is at least one of amines, tertiary amines, acid anhydrides, borides or other types of epoxy curing agents; the preferred epoxy curing agent is methylhexahydrophthalic anhydride.

[0019] The present invention also discloses a method for preparing the environmentally friendly six-proof paint, comprising the following steps: The raw materials are weighed according to the formula, and the epoxy resin, modified polyurethane, dispersant, modified filler, antifreeze agent and acetone are mixed and dispersed into a paint slurry at high speed. The mixture is ground with a sand mill, and the mildew inhibitor, leveling agent and anti-settling agent are added and mixed evenly. Finally, the curing agent is added and mixed evenly to obtain the environmentally friendly six-proof paint.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention uses epoxy resin and modified polyurethane as the main film-forming substances and acetone as the solvent, which can effectively reduce VOC emissions. VOC emissions are extremely low and meet environmental protection requirements. The flexible siloxane segment of the polyurethane molecular chain complements the rigid structure of the epoxy resin, effectively resisting cracking and peeling caused by thermal expansion and contraction or external forces, thereby improving the durability and reliability of the coating. 2) The present invention improves the water resistance and weather resistance of the conformal coating by introducing silicone oil into the polyurethane. Its flexible chain segments can effectively absorb and disperse energy when subjected to external impact, providing impact resistance and toughening, thereby improving the mechanical properties of the coating. The introduction of ethyl 4-aminocinnamate introduces carbon-carbon double bonds into the polyurethane molecule, further improving the water resistance of the coating. Subsequently, the reaction with 2-hydroxyethyl methacrylate phosphate introduces phosphate groups and hydroxyl groups into the polyurethane molecule. This not only improves the chemical corrosion resistance and weather resistance of the conformal coating, enabling it to remain stable in complex environments for a long time, but also cross-links with the epoxy resin, improving the adhesion of the conformal coating, allowing it to firmly adhere to the substrate surface and prevent shedding or delamination. 3) The present invention grafts carbon nanotubes with heptadecenylamineethylimidazoline quaternary ammonium salt to significantly improve the dispersibility of carbon nanotubes in the resin system, thereby improving the interfacial bonding performance of the six-proof paint and helping to improve the mechanical strength of the coating. Its hydrophobic and flexible long chains are conducive to further improving the flexibility and water resistance of the six-proof paint. At the same time, the grafted quaternary ammonium salt can release quaternary ammonium cations when the coating is damaged. These cations can be rapidly adsorbed on the metal surface to form a protective barrier, inhibiting the occurrence of electrochemical corrosion and playing a corrosion-inhibiting role. In addition, the quaternary ammonium salt also has excellent broad-spectrum antibacterial properties and can effectively inhibit the growth of mold and bacteria, thereby extending the anti-mildew time of the coating and improving the long-term performance of the coating in complex environments. DETAILED DESCRIPTION

[0021] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0022] The sources of some raw materials used in the present invention are as follows: Epoxy resin, brand E-44, was purchased from Hebei Jingxin Innovation Materials Co., Ltd.

[0023] Dimethylhydroxy silicone oil, with a viscosity of 100 cs, was purchased from Shenzhen Jipeng Silicone Fluoride Materials Co., Ltd.

[0024] Carbon nanotubes with a particle size of 10 nm were purchased from Shandong Tanfeng New Materials Technology Co., Ltd.

[0025] Example 1 A method for preparing an environmentally friendly six-proof paint comprises the following steps: 400g epoxy resin, 152g modified polyurethane, 43.5g sodium polyacrylate, 154.7g modified filler, 13.8g tristyrylphenol polyoxyethylene ether, and 80g acetone were mixed and dispersed into a paint slurry at high speed. The mixture was ground to 60μm with a sand mill. 16.4g chitosan, 15.2g leveling agent BYK-111, and 14.8g fumed silica were added and mixed evenly. Finally, 40g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0026] The preparation method of modified polyurethane is as follows: (1) Add 190 g of dimethylhydroxy silicone oil and 0.8 g of stannous octoate into a reaction vessel and stir evenly. Then add 40 g of hexamethylene diisocyanate and react at 60 °C for 3 h to obtain silicone oil-modified polyurethane. (2) 35 g of ethyl 4-aminocinnamate was added to 138 g of silicone oil-modified polyurethane and stirred for 10 min. Then, 0.6 g of 2,6-di-tert-butyl-p-cresol was added and the mixture was reacted at 60 °C for 5 h. Then, 20 g of 2-hydroxyethyl methacrylate phosphate and 0.3 g of ammonium persulfate were added and the mixture was reacted at 60 °C for 3 h. After the reaction was completed, the unreacted matter was evaporated under reduced pressure to obtain modified polyurethane.

[0027] The preparation method of the modified filler is as follows: 50g of carbon nanotubes were dispersed in 200mL of concentrated sulfuric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 25g of pretreated carbon nanotubes were dispersed in 200mL of 50wt% ethanol aqueous solution, 4.2g of vinyltriisopropoxysilane was added, heated at 60℃ for 3h, filtered, the solid was collected, washed and dried to obtain activated carbon nanotubes; 6.5g of heptadecenylamineethylimidazoline quaternary ammonium salt was dissolved in 100mL of toluene, activated carbon nanotubes and 0.5g of benzoyl peroxide were added in sequence, heated at 80℃ for 4h, filtered, the solid was collected, washed and dried to obtain modified filler.

[0028] Example 2 A method for preparing an environmentally friendly six-proof paint comprises the following steps: 300g epoxy resin, 100g modified polyurethane, 30.3g sodium polyacrylate, 100g modified filler, 10g tristyrylphenol polyoxyethylene ether, and 50g acetone were mixed and dispersed into a paint slurry at high speed. The mixture was ground to 60μm with a sand mill. 10.5g chitosan, 10.2g leveling agent BYK-111, and 10.5g fumed silica were added and mixed evenly. Finally, 30g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0029] The preparation method of modified polyurethane is as follows: (1) Add 180 g of dimethylhydroxy silicone oil and 0.5 g of stannous octoate into a reaction vessel and stir evenly. Then add 30 g of hexamethylene diisocyanate and react at 60 °C for 3 h to obtain silicone oil-modified polyurethane. (2) Add 20 g of ethyl 4-aminocinnamate to 100 g of silicone oil-modified polyurethane and stir for 10 min. Then add 0.1 g of 2,6-di-tert-butyl-p-cresol and react at 60 °C for 5 h. Then add 10 g of 2-hydroxyethyl methacrylate phosphate and 0.1 g of ammonium persulfate and continue to react at 60 °C for 3 h. After the reaction is completed, remove the unreacted product under reduced pressure to obtain modified polyurethane.

[0030] The preparation method of the modified filler is as follows: 50g of carbon nanotubes were dispersed in 200mL of concentrated sulfuric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 20g of pretreated carbon nanotubes were dispersed in 200mL of 50wt% ethanol aqueous solution, 3g of vinyltriisopropoxysilane was added, heated at 60℃ for 3h, filtered, the solid was collected, washed and dried to obtain activated carbon nanotubes; 5g of heptadecenylamineethylimidazoline quaternary ammonium salt was dissolved in 100mL of toluene, activated carbon nanotubes and 0.3g of benzoyl peroxide were added in sequence, heated at 80℃ for 4h, filtered, the solid was collected, washed and dried to obtain modified filler.

[0031] Example 3 A method for preparing an environmentally friendly six-proof paint comprises the following steps: 500g epoxy resin, 200g modified polyurethane, 50g sodium polyacrylate, 200g modified filler, 20g tristyrylphenol polyoxyethylene ether, and 100g acetone were mixed and dispersed into a paint slurry at high speed, and then ground to 60μm with a sand mill. 20g chitosan, 20g leveling agent BYK-111, and 20g fumed silica were added and mixed evenly. Finally, 50g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0032] The preparation method of modified polyurethane is as follows: (1) Add 200 g of dimethylhydroxy silicone oil and 1 g of stannous octoate into a reaction vessel and stir evenly. Then add 50 g of hexamethylene diisocyanate and react at 60 °C for 3 h to obtain silicone oil-modified polyurethane. (2) Add 50 g of ethyl 4-aminocinnamate to 150 g of silicone oil-modified polyurethane and stir for 10 min. Then add 1 g of 2,6-di-tert-butyl-p-cresol and react at 60 °C for 5 h. Then add 30 g of 2-hydroxyethyl methacrylate phosphate and 0.5 g of ammonium persulfate and continue to react at 60 °C for 3 h. After the reaction is completed, remove the unreacted matter under reduced pressure to obtain modified polyurethane.

[0033] The preparation method of the modified filler is as follows: 50g of carbon nanotubes were dispersed in 200mL of concentrated sulfuric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 30g of pretreated carbon nanotubes were dispersed in 200mL of 50wt% ethanol aqueous solution, 5g of vinyltriisopropoxysilane was added, heated at 60℃ for 3h, filtered, the solid was collected, washed and dried to obtain activated carbon nanotubes; 8g of heptadecenylamineethylimidazoline quaternary ammonium salt was dissolved in 100mL of toluene, activated carbon nanotubes and 0.8g of benzoyl peroxide were added in sequence, heated at 80℃ for 4h, filtered, the solid was collected, washed and dried to obtain modified filler.

[0034] Comparative Example 1 A method for preparing an environmentally friendly six-conformal coating is similar to that of Example 1, except that the filler is carbon nanotubes, and comprises the following steps: 400g epoxy resin, 152g modified polyurethane, 43.5g sodium polyacrylate, 154.7g modified filler, 13.8g tristyrylphenol polyoxyethylene ether, and 80g acetone were mixed and dispersed into a paint slurry at high speed. The mixture was ground to 60μm with a sand mill. 16.4g chitosan, 15.2g leveling agent BYK-111, and 14.8g fumed silica were added and mixed evenly. Finally, 40g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0035] The preparation method of modified polyurethane is as follows: (1) Add 190 g of dimethylhydroxy silicone oil and 0.8 g of stannous octoate into a reaction vessel and stir evenly. Then add 40 g of hexamethylene diisocyanate and react at 60 °C for 3 h to obtain silicone oil-modified polyurethane. (2) 35 g of ethyl 4-aminocinnamate was added to 138 g of silicone oil-modified polyurethane and stirred for 10 min. Then, 0.6 g of 2,6-di-tert-butyl-p-cresol was added and the mixture was reacted at 60 °C for 5 h. Then, 20 g of 2-hydroxyethyl methacrylate phosphate and 0.3 g of ammonium persulfate were added and the mixture was reacted at 60 °C for 3 h. After the reaction was completed, the unreacted matter was evaporated under reduced pressure to obtain modified polyurethane.

[0036] Comparative Example 2 A method for preparing an environmentally friendly six-conformal coating is similar to that of Example 1, except that the modified polyurethane is silicone oil-modified polyurethane, and specifically comprises the following steps: 400g epoxy resin, 152g modified polyurethane, 43.5g sodium polyacrylate, 154.7g modified filler, 13.8g tristyrylphenol polyoxyethylene ether, and 80g acetone were mixed and dispersed into a paint slurry at high speed. The mixture was ground to 60μm with a sand mill. 16.4g chitosan, 15.2g leveling agent BYK-111, and 14.8g fumed silica were added and mixed evenly. Finally, 40g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0037] The preparation method of modified polyurethane is as follows: 190 g of dimethylhydroxy silicone oil and 0.8 g of stannous octoate were added to a reaction container and stirred evenly. Then 40 g of hexamethylene diisocyanate was added and reacted at 60° C. for 3 h to obtain silicone oil-modified polyurethane, i.e., modified polyurethane.

[0038] The preparation method of the modified filler is as follows: 50g of carbon nanotubes were dispersed in 200ml of concentrated sulfuric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 25g of pretreated carbon nanotubes were dispersed in 200mL of 50wt% ethanol aqueous solution, 4.2g of vinyltriisopropoxysilane was added, heated at 60℃ for 3h, filtered, the solid was collected, washed and dried to obtain activated carbon nanotubes; 6.5g of heptadecenylamineethylimidazoline quaternary ammonium salt was dissolved in 100mL of toluene, activated carbon nanotubes and 0.5g of benzoyl peroxide were added in sequence, heated at 80℃ for 4h, filtered, the solid was collected, washed and dried to obtain modified filler.

[0039] Comparative Example 3 A method for preparing an environmentally friendly six-conformal coating is similar to that of Example 1, except that 2-hydroxyethyl methacrylate phosphate is not added during the preparation of the modified polyurethane. The method specifically comprises the following steps: 400g epoxy resin, 152g modified polyurethane, 43.5g sodium polyacrylate, 154.7g modified filler, 13.8g tristyrylphenol polyoxyethylene ether, and 80g acetone were mixed and dispersed into a paint slurry at high speed. The mixture was ground to 60μm with a sand mill. 16.4g chitosan, 15.2g leveling agent BYK-111, and 14.8g fumed silica were added and mixed evenly. Finally, 40g methylhexahydrophthalic anhydride was added and mixed evenly to obtain an environmentally friendly six-proof paint.

[0040] The preparation method of modified polyurethane is as follows: (1) Add 190 g of dimethylhydroxy silicone oil and 0.8 g of stannous octoate into a reaction vessel and stir evenly. Then add 40 g of hexamethylene diisocyanate and react at 60 °C for 3 h to obtain silicone oil-modified polyurethane. (2) 35 g of ethyl 4-aminocinnamate was added to 138 g of silicone oil-modified polyurethane and stirred for 10 min. Then, 0.6 g of 2,6-di-tert-butyl-p-cresol was added and reacted at 60 °C for 5 h. After the reaction was completed, the unreacted matter was evaporated under reduced pressure to obtain modified polyurethane.

[0041] The preparation method of the modified filler is as follows: 50g of carbon nanotubes were dispersed in 200ml of concentrated sulfuric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 25g of pretreated carbon nanotubes were dispersed in 200mL of 50wt% ethanol aqueous solution, 4.2g of vinyltriisopropoxysilane was added, heated at 60℃ for 3h, filtered, the solid was collected, washed and dried to obtain activated carbon nanotubes; 6.5g of heptadecenylamineethylimidazoline quaternary ammonium salt was dissolved in 100mL of toluene, activated carbon nanotubes and 0.5g of benzoyl peroxide were added in sequence, heated at 80℃ for 4h, filtered, the solid was collected, washed and dried to obtain modified filler.

[0042] Performance Testing The environmentally friendly six-proof paint prepared in Examples 1-3 and Comparative Examples 1-3 was stirred at room temperature for 10 minutes and then evenly sprayed onto the circuit board with a coating thickness of 0.1 mm. The coating was cured at 25° C. for 7 days to obtain a coating for testing.

[0043] Wear resistance test: refer to GB / T 1768-2006 "Paints and varnishes - Determination of abrasion resistance - Rotating rubber grinding wheel method"; Adhesion test: refer to GB / T 5210-2006 "Paints and varnishes adhesion test by pull-off method"; Corrosion resistance test: refer to GB / T 31588.1-2015 "Paints and varnishes - Determination of resistance to cyclic corrosion environments - Part 1: Wet (salt spray) / dry / humid atmosphere"; Antibacterial rate test: refer to GB / T 21866-2008 "Determination of antibacterial properties and antibacterial effects of antibacterial coatings (paint films)"; Impact resistance test: Tested in accordance with GB / T1731-2020 "Determination of flexibility of paint and putty films"; Water contact angle test: using PZ-200SD contact angle meter, the test results are shown in Table 1: Table 1 Test results of environmentally friendly six-proof paint performance

[0044] It can be seen from the experimental results in Table 1 that the environmentally friendly six-conformal paint prepared in the present invention has good wear and scratch resistance, adhesion, salt spray corrosion resistance, antibacterial, impact resistance and water resistance and antifouling properties.

[0045] The volume resistivity of the environmentally friendly six-proof paint of Example 1 was tested according to the standard GB / T 1410-2006, and the volume resistivity was 1.9×10 16 (Ω·m), the environmentally friendly six-proof paint prepared by the present invention also has excellent insulation properties.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. An environmentally friendly six-proof paint, characterized in that: The invention comprises the following components in parts by weight: 30-50 parts of epoxy resin, 10-20 parts of modified polyurethane, 3-5 parts of dispersant, 1-2 parts of mildew inhibitor, 1-2 parts of leveling agent, 1-2 parts of anti-settling agent, 10-20 parts of modified filler, 1-2 parts of antifreeze agent, 3-5 parts of curing agent, and 5-10 parts of acetone; The preparation method of the modified polyurethane is as follows: (1) Add dimethylhydroxy silicone oil and stannous octoate into a reaction vessel and stir evenly, then add hexamethylene diisocyanate and heat to react to obtain silicone oil modified polyurethane; (2) Ethyl 4-aminocinnamate is added to the silicone oil modified polyurethane, stirred, then 2,6-di-tert-butyl-p-cresol is added, stirred for reaction, and then 2-hydroxyethyl methacrylate phosphate and an initiator are added, heated for reaction, and the modified polyurethane is obtained.

2. The environmentally friendly conformal coating according to claim 1, characterized in that: In step (1), the mass ratio of the dimethylhydroxy silicone oil, stannous octoate, and hexamethylene diisocyanate is 18-20:0.05-0.1:3-5.

3. The environmentally friendly conformal coating according to claim 2, characterized in that: In step (2), the mass ratio of ethyl 4-aminocinnamate, silicone oil-modified polyurethane, 2,6-di-tert-butyl-p-cresol, 2-hydroxyethyl methacrylate phosphate, and initiator is 2-5:10-15:0.01-0.1:1-3:0.01-0.

05.

4. The environmentally friendly conformal coating according to claim 1, characterized in that: In step (1), the temperature of the temperature-raising reaction is 50-80°C, and the time is 2-4 hours; in step (2), the temperature of the stirring reaction is 50-70°C, and the time is 4-6 hours; the temperature of the heating reaction is 60-80°C, and the reaction time is 2-4 hours.

5. The environmentally friendly conformal coating according to claim 1, characterized in that: The preparation method of the modified filler is as follows: The carbon nanotubes are dispersed in concentrated sulfuric acid and subjected to ultrasonic heating treatment to obtain pretreated carbon nanotubes. The pretreated carbon nanotubes are dispersed in an ethanol aqueous solution, a vinyl silane coupling agent is added, and the mixture is heated to react to obtain activated carbon nanotubes. Heptadecenylaminoethylimidazoline quaternary ammonium salt is dissolved in toluene, and the activated carbon nanotubes and ammonium persulfate are added in sequence and heated to react to obtain the modified filler.

6. The environmentally friendly conformal coating according to claim 5, characterized in that: The mass ratio of the pretreated carbon nanotubes, the vinyl silane coupling agent, and the heptadecenylamine ethyl imidazoline quaternary ammonium salt is 20-30:3-5:5-8.

7. The environmentally friendly conformal coating according to claim 1, characterized in that: The dispersant is at least one of sodium polyacrylate, trisodium phosphate, alkylphenol polyoxyethylene ether, and sodium alkyl aryl sulfonate.

8. The environmentally friendly conformal coating according to claim 1, characterized in that: The anti-mildew agent is chitin.

9. The environmentally friendly conformal coating according to claim 1, characterized in that: The antifreeze agent is tristyrylphenol polyoxyethylene ether.

10. A method for preparing the environmentally friendly conformal coating according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: weighing each component according to the formula, mixing epoxy resin, modified polyurethane, dispersant, modified filler, antifreeze agent and acetone, dispersing the mixture into a paint slurry at high speed, grinding the mixture with a sand mill, adding mildew inhibitor, leveling agent and anti-settling agent and mixing the mixture evenly, and finally adding curing agent and mixing the mixture evenly to obtain the environmentally friendly six-proof paint.

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