A fluorine-free water and oil repellent coating composition and a method for preparing the same

Abstract

This invention relates to the field of coating technology, and more particularly to a fluorine-free waterproof and oil-resistant coating composition and its preparation method, comprising the following raw materials by weight: 2-4 parts hydrogenated castor oil, 6-10 parts vinyltrimethoxysilane, 0.5-1 part photoinitiator, 0.1-0.5 parts leveling agent, 7-10 parts ethyl acetate, and 70-80 parts copolymer solution. The coating composition obtained by this invention exhibits good hardness, abrasion resistance, and chemical resistance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a fluorine-free waterproof and oil-proof coating composition and its preparation method. Background Technology

[0002] Traditional fluorinated waterproofing and oil-repellent agents rely on perfluorinated / polyfluoroalkyl substances to achieve excellent hydrophobic and oleophobic properties. However, during production, use, and disposal, they release persistent pollutants such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These pollutants are not only difficult to degrade but also easily accumulate through bioaccumulation, posing a threat to the ecological environment and human health. In applications such as membranes, fabrics, and electronic appliances, fluorinated-free waterproofing and oil-repellent coatings must not only resist the erosion of various liquids such as sweat, oil stains, and rainwater but also meet comprehensive performance requirements such as abrasion resistance, weather resistance, and fingerprint resistance.

[0003] Currently, mainstream fluorine-free technologies mainly include silicone-based, polyurethane-based, and nanocomposite materials. Silicone-based coatings use siloxanes as the main chain, reducing surface energy through molecular design to form a flexible and weather-resistant hydrophobic layer. Polyurethane coatings achieve low VOC emissions through an aqueous system; the ester and urea groups in their molecules endow the coating with good adhesion, hydrolysis resistance, and chemical stability. Nanocomposite materials introduce inorganic particles such as silica to construct a micro-nano rough structure on the surface, achieving a superhydrophobic state with a contact angle greater than 150°. Electronic products and membrane materials come into long-term contact with human sweat and oils; fluorine-free coatings can prevent performance degradation caused by PFAS migration. Drones, outdoor sensors, and other devices rely on the high weather resistance and environmental compatibility of fluorine-free materials to achieve long-lasting protection in harsh environments.

[0004] In existing technologies, fluorine-free alternatives typically offer good water resistance, but they struggle to effectively resist common oily substances such as cooking oils, cosmetics, and sunscreens. Furthermore, fluorine-free coatings have relatively low hardness, causing their protective effect to rapidly diminish after frequent friction and scratching. Compared to tightly cross-linked fluorocarbon chains, the structures of some fluorine-free polymers are more vulnerable to chemicals such as alcohol, detergents, and sweat, leading to the breakdown or rinsing off of their protective properties. Summary of the Invention

[0005] To address the problems mentioned in the background section, the present invention provides a fluorine-free waterproof and oil-resistant coating composition and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A fluorine-free waterproof and oil-resistant coating composition comprises, by weight, the following raw materials: 2-4 parts hydrogenated castor oil, 6-10 parts vinyltrimethoxysilane, 0.5-1 part photoinitiator, 0.1-0.5 parts leveling agent, 7-10 parts ethyl acetate, and 70-80 parts copolymer solution.

[0007] Furthermore, the photoinitiator is selected from at least one of photoinitiator 184, photoinitiator 1173, or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0008] Furthermore, the leveling agent is selected from at least one of leveling agent 333, leveling agent 306, leveling agent 358 or leveling agent 361.

[0009] Furthermore, the copolymer solution is a binary copolymer solution, wherein the first monomer is α-pinene, and the second monomer is an acrylate monomer containing a long-chain alkyl group, with the general structural formula: CH2=C(R1)COOR2, where R1 is H or CH3, and R2 is a C8-C18 straight-chain or branched alkyl group.

[0010] Furthermore, the copolymer solution is prepared by the following steps: α-Pinene was added to ethyl acetate, and the mixture was heated to 75-82°C under nitrogen protection. A mixture of acrylate containing long-chain alkyl groups and an initiator was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 5-6 hours. After the reaction was completed, the mixture was cooled to below 40°C and filtered to obtain a copolymer solution.

[0011] Furthermore, the mass ratio of α-pinene, ethyl acetate and acrylate containing long-chain alkyl groups is (68-70):(230-270):(102-118).

[0012] Furthermore, the initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, or azobisisoheptanenitrile, and the amount used is 0.8-1.2% of the total mass of α-pinene and the acrylate containing long-chain alkyl groups.

[0013] According to another aspect of the present invention, a method for preparing the above-described coating composition is provided, comprising the following steps: S1. Mix hydrogenated castor oil and ethyl acetate, and stir for 15-20 minutes to obtain a pre-dispersed slurry; S2. Add copolymer solution, vinyltrimethoxysilane, photoinitiator and leveling agent to pre-dispersed slurry, stir for 20-30 minutes, mix evenly to obtain coating composition.

[0014] Furthermore, the stirring speed in step S1 is 800-1000 rpm, and the stirring speed in step S2 is 400-600 rpm.

[0015] The beneficial effects of this invention are: 1. The copolymer solution of the present invention is prepared by a specific process: under nitrogen protection, α-pinene is dissolved in ethyl acetate and heated to a suitable temperature, then a mixture of acrylate containing long-chain alkyl groups and an initiator is added dropwise. After reaction, cooling, and filtration, a binary copolymer is obtained. These copolymers have long-chain alkyl groups grafted onto their main chain. During the coating film formation process, these long-chain alkyl groups easily migrate to and accumulate on the coating surface, forming a low surface energy surface layer. Based on this structural characteristic, compared with some existing fluorine-free alternatives, it exhibits more positive protective performance against oily substances such as cooking oil, cosmetics, and sunscreen, helping to reduce the adhesion or penetration of oily substances on the coating surface. This provides a certain improvement in protection for the casings of consumer electronics products that come into contact with hand oils and cosmetics.

[0016] 2. In this invention, hydrogenated castor oil and ethyl acetate are first stirred at high speed to prepare a pre-dispersed slurry, which causes the hydrogenated castor oil to form nano-sized microcrystals. Subsequently, copolymer solution, vinyltrimethoxysilane and other raw materials are added and mixed. During the film-forming stage, a double cross-linked network is formed under the action of a photoinitiator. The residual double bonds of the copolymer and the vinyl polymerization of vinyltrimethoxysilane form C-C covalent bonds. Vinyltrimethoxysilane hydrolyzes and condenses to form Si-O-Si covalent bonds. Furthermore, the hydrogenated castor oil nanocrystals will combine with the cross-linked network through hydrogen bonds, which has a positive impact on the hardness of the coating. When faced with frequent friction and scratching, it may reduce the probability of coating damage, delay the decay of the protective effect to a certain extent, and avoid the rapid decline of protective performance due to insufficient hardness.

[0017] 3. The double cross-linked network in the coating of this invention has unique structural advantages. The Si-O-Si covalent bonds themselves possess good chemical stability and may be more resistant to chemical corrosion compared to a simple carbon chain structure. Simultaneously, the tight double cross-linked network structure also, to a certain extent, prevents components such as alcohol, detergents, and sweat from penetrating into the coating and reacting with the core structure. This helps reduce the possibility of the protective performance being damaged or washed away by chemical reactions, allowing the coating to maintain a relatively stable protective state for a certain period after contact with these common chemical substances. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a fluorine-free waterproof and oil-resistant coating composition, preferably comprising the following raw materials in parts by weight: 2-4 parts hydrogenated castor oil, specifically 2, 3, or 4 parts; Vinyltrimethoxysilane 6-10 parts, specifically 6 parts, 7 parts, 8 parts, 9 parts and 10 parts; The photoinitiator is 0.5-1 part, specifically 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts and 1 part.

[0020] The leveling agent is applied in amounts of 0.1-0.5 parts, specifically 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, and 0.5 parts. Ethyl acetate 7-10 parts, specifically 7 parts, 8 parts, 9 parts and 10 parts; The copolymer solution contains 70-80 parts, specifically 70, 71, 72, 73, 74, 75, 76, 77, 78, 79 and 80 parts.

[0021] In the coating composition provided by the present invention, the photoinitiator is preferably selected from at least one of photoinitiator 184, photoinitiator 1173 or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, specifically photoinitiator 184 (hydroxycyclohexanephenyl ketone), photoinitiator 1173 (α-hydroxyisobutyrylbenzene) or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0022] In the coating composition provided by the present invention, the leveling agent is preferably selected from at least one of leveling agent 333 (BYK-333), leveling agent 306 (BYK-306), leveling agent 358 (BYK-358) or leveling agent 361 (BYK-361), specifically leveling agent 333, leveling agent 306, leveling agent 358 or leveling agent 361.

[0023] In the coating composition provided by the present invention, the copolymer solution is a binary copolymer solution, wherein the first monomer is α-pinene, the second monomer is an acrylate monomer containing a long-chain alkyl group, and its general structural formula is: CH2=C(R1)COOR2, where R1 is H or CH3, and R2 is a C8-C18 straight-chain or branched alkyl group.

[0024] When R1 is H, the second monomer can specifically be CH2=CH-COO-(CH2)7-CH3 (n-octyl acrylate), CH2=CH-COO-CH2-CH(C2H5)-(CH2)3-CH3 (isooctyl acrylate), CH2=CH-COO-(CH2)8-CH3 (n-nonyl acrylate), and CH2=CH-COO-(CH2) 11 -CH3 (lauryl acrylate).

[0025] When R1 is CH3, the second monomer can specifically be CH2=C(CH3)-COO-(CH2).11 -CH3 (lauryl methacrylate) and CH2=C(CH3)-COO-(CH2) 17 -CH3 (stearyl methacrylate).

[0026] In the coating composition provided by the present invention, the copolymer solution is prepared by the following steps: α-Pinene was added to ethyl acetate, and the mixture was heated under nitrogen protection. A mixture of acrylate containing long-chain alkyl groups and an initiator was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 5-6 hours. After the reaction was completed, the mixture was cooled to below 40°C and filtered to obtain a copolymer solution.

[0027] The preferred temperature for the above-mentioned heating is 75-82℃, specifically 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 87℃ and 82℃.

[0028] The preferred mass ratio of the above-mentioned α-pinene, ethyl acetate and acrylate containing long-chain alkyl groups is (68-70):(230-270):(102-118), specifically (68:230:102), (68:235:105), (70:240:118), (68:250:104), (68:270:106), (69:245:107), (68:250:105), (70:250:107), (69:270:102), (70:265:115), (68:260:103) and (70:270:118).

[0029] The initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide, or azobisisoheptanenitrile, specifically azobisisobutyronitrile, benzoyl peroxide, or azobisisoheptanenitrile.

[0030] The preferred ratio of the above-mentioned initiator is 0.8-1.2% of the total mass of α-pinene and acrylate containing long-chain alkyl groups, specifically 0.8%, 0.9%, 1%, 1.1% and 1.2%.

[0031] The present invention also provides a method for preparing the above-mentioned coating composition, comprising the following steps: S1. Mix hydrogenated castor oil and ethyl acetate, and stir for 15-20 minutes to obtain a pre-dispersed slurry; S2. Add copolymer solution, vinyltrimethoxysilane, photoinitiator and leveling agent to pre-dispersed slurry, stir for 20-30 minutes, mix evenly to obtain coating composition.

[0032] In the preparation method provided by the present invention, the stirring speed in step S1 is preferably 800-1000 rpm, specifically 800 rpm, 850 rpm, 900 rpm, 950 rpm and 1000 rpm.

[0033] In the preparation method provided by the present invention, the stirring speed in step S2 is preferably 400-600 rpm, specifically 400 rpm, 450 rpm, 500 rpm, 550 rpm and 600 rpm.

[0034] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0035] Example 1 The copolymer solution is prepared by the following steps: 6.8 g of α-pinene was added to 23 g of ethyl acetate. Under nitrogen protection, the mixture was heated to 75 °C. A mixture of 10.2 g of n-octyl acrylate and 0.136 g of azobisisobutyronitrile was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 5 h. After the reaction was completed, the mixture was cooled to 40 °C and filtered to obtain the copolymer solution.

[0036] Example 2 The copolymer solution is prepared by the following steps: 6.9 g of α-pinene was added to 245 g of ethyl acetate. Under nitrogen protection, the mixture was heated to 79 °C. A mixture of 10.7 g of lauryl acrylate and 0.176 g of azobisisobutyronitrile was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 5.5 h. After the reaction was completed, the mixture was cooled to 30 °C and filtered to obtain the copolymer solution.

[0037] Example 3 The copolymer solution is prepared by the following steps: 7g of α-pinene was added to 27g of ethyl acetate. Under nitrogen protection, the mixture was heated to 82℃. A mixture of 11.8g of stearyl methacrylate and 0.226g of azobisisobutyronitrile was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 6 hours. After the reaction was completed, the mixture was cooled to 20℃ and filtered to obtain the copolymer solution.

[0038] Example 4 A method for preparing a fluorine-free waterproof and oil-resistant coating composition includes the following steps: S1. Mix 2 parts hydrogenated castor oil and 7 parts ethyl acetate by weight, and stir at 800 rpm for 15 min to obtain a pre-dispersed slurry; S2. Add 70 parts of the copolymer solution prepared in Example 1, 6 parts of vinyltrimethoxysilane, 0.5 parts of photoinitiator 184 and 0.1 parts of leveling agent 333 to the pre-dispersed slurry, stir at 400 rpm for 20 min, mix evenly, and obtain the coating composition.

[0039] Example 5 A method for preparing a fluorine-free waterproof and oil-resistant coating composition includes the following steps: S1. Mix 3 parts by weight of hydrogenated castor oil and 8 parts by weight of ethyl acetate, and stir at 900 rpm for 17 min to obtain a pre-dispersed slurry; S2. Add 78 parts of the copolymer solution prepared in Example 2, 8 parts of vinyltrimethoxysilane, 0.7 parts of photoinitiator 1173 and 0.3 parts of leveling agent 306 to the pre-dispersed slurry, stir at 500 rpm for 25 min, mix evenly, and obtain the coating composition.

[0040] Example 6 A method for preparing a fluorine-free waterproof and oil-resistant coating composition includes the following steps: S1. Mix 4 parts by weight of hydrogenated castor oil and 10 parts by weight of ethyl acetate, and stir at 1000 rpm for 20 min to obtain a pre-dispersed slurry; S2. Add 80 parts of the copolymer solution prepared in Example 3, 10 parts of vinyltrimethoxysilane, 1 part of TPO and 0.5 parts of leveling agent 358 to the pre-dispersed slurry, stir at 600 rpm for 30 min, mix evenly to obtain the coating composition.

[0041] Comparative Example 1 The difference between this comparative example and Example 4 is that n-octyl acrylate is used instead of the copolymer solution prepared in Example 1, while the remaining steps are the same as in Example 4.

[0042] Comparative Example 2 The difference between this comparative example and Example 5 is that α-pinene is used instead of the copolymer solution prepared in Example 2, while the remaining steps are the same as in Example 5.

[0043] Comparative Example 3 The difference between this comparative example and Example 6 is that stearic acid methacrylate is used instead of the copolymer solution prepared in Example 3, while the remaining steps are the same as in Example 6.

[0044] Cut the PET film into several 15cm × 20cm substrate pieces, wipe them clean with ethanol, and let them air dry. Using a wire bar coater, uniformly coat the coating compositions prepared in Examples 4-6 and Comparative Examples 1-3 onto the prepared substrates to a thickness of 50μm. Immediately place the coated samples under a UV curing device for curing, irradiating them for 5 seconds at a wavelength of 365nm and a light intensity of not less than 80 mW / cm². After curing, place the samples in a standard laboratory environment (temperature 23±2℃, relative humidity 50±10%) for 24 hours, and then conduct performance tests.

[0045] (I) Waterproofing test: Using a contact angle meter, 5 μL of ultrapure water droplets are dropped at different locations on the sample surface. Static contact angle images are recorded and the angle values ​​are measured. At least 5 points are measured for each sample, and the average value is taken.

[0046] (II) Oil resistance test: Use a contact angle meter and select vegetable oil for testing. The method is the same as the water resistance test.

[0047] The results are shown in Table 1:

[0048]

[0049] (III) Abrasion resistance test: A rubbing fastness tester was used to rub the coating surface 500 times under a pressure of 1 kPa. The rubbing tester stroke was set to 100 mm and the rubbing speed to 30 cycles / min. The water contact angle was measured at the center of the rubbing area, and the retention rate was calculated as follows: Retention rate (%) = (contact angle after rubbing / initial contact angle) × 100%. The results are shown in Table 2.

[0050]

[0051] (IV) Chemical Corrosion Resistance Test: Prepare artificial sweat with a formula of 5 g / L sodium chloride, 1 g / L urea, and 1 g / L lactic acid. Adjust the pH to 4.3 with sodium hydroxide. Also prepare a 0.5% standard household neutral detergent solution (refer to GB / T 9985-2022 "Detergents for Hand Washing Dishwashing"). Cut a white cotton cloth to the same size as the sample and completely saturate it in the test solution (artificial sweat or detergent solution). Wring out excess liquid until 100% wet. Cover the coated sample surface with the wet cotton cloth, ensuring complete contact without air bubbles. Place the covered sample in a sealed bag or the container of the sweat resistance tester, sealing it to prevent liquid evaporation. Place the container in a constant temperature oven at 40°C for 4 hours to simulate an accelerated process of intensive use or cleaning. Remove the sample, gently rinse the surface with deionized water, and blot dry with a soft cloth. Place the sample in a standard environment for 1 hour to allow it to stabilize. Repeat 50 cycles to simulate long-term use. The water contact angle was measured after the test, and the retention rate was calculated. The results are shown in Table 3.

[0052]

[0053] As shown in Table 1, in the copolymer solutions of Examples 4-6, α-pinene and acrylate monomers containing long-chain alkyl groups formed binary copolymers through a copolymerization reaction. During film formation, the long-chain alkyl groups on the copolymer backbone migrate to and accumulate on the coating surface, forming a low surface energy surface structure. This improves the coating's ability to repel water and oily substances (such as vegetable oil), resulting in a higher water contact angle (115°-135°) and oil contact angle (80°-93°).

[0054] Comparative Example 1 lacks copolymerization of α-pinene, failing to form a synergistic structure between long-chain alkyl groups and α-pinene. Insufficient long-chain alkyl groups enriched on the surface result in a significant decrease in contact angle. Comparative Example 2, although containing some hydrophobicity in α-pinene, lacks copolymerization of long-chain alkyl groups, failing to form a low-surface-energy enrichment layer, resulting in an even lower contact angle. Comparative Example 3, while containing long-chain alkyl groups, lacks copolymerization of α-pinene, failing to leverage the rigid structure of α-pinene to promote the directional alignment of long-chain alkyl groups, leading to a weakened surface enrichment effect.

[0055] As shown in Table 2, the residual double bonds in the copolymer polymerize with the vinyl group of vinyltrimethoxysilane under the action of a photoinitiator, forming stable C-C bonds. After hydrolysis, vinyltrimethoxysilane condenses to form a Si-O-Si network, further enhancing the structural strength of the coating. The nanocrystals formed by hydrogenated castor oil in the pre-dispersed slurry bond with the cross-linked network through hydrogen bonds, improving the hardness and wear resistance of the coating.

[0056] Comparative Example 1 lacks α-pinene copolymerization, preventing the formation of a double cross-linked network, resulting in a loose coating structure and poor wear resistance. Comparative Example 2, while potentially forming some cross-links with α-pinene, lacks long-chain alkyl copolymerization, leading to insufficient cross-link density and even worse wear resistance. Comparative Example 3, although providing some hydrophobicity with long-chain alkyl groups, lacks the rigid structure and double cross-linked network of α-pinene, making the coating easily worn.

[0057] As shown in Table 3, the Si-O-Si bonds in Examples 4-6 have high bond energies, exhibiting excellent resistance to acids, alkalis, and organic solvents, effectively blocking the penetration of artificial sweat and cleaning agents. The double cross-linked network forms a dense barrier, reducing the contact between chemicals and the internal structure of the coating, and delaying the degradation of protective performance.

[0058] Comparative Example 1: The coating structure is loose, allowing chemicals to easily penetrate and resulting in a significant decrease in the contact angle. Comparative Example 2: Although α-pinene may possess some hydrophobicity, it lacks a cross-linked network, making the coating structure easily damaged by chemicals. Comparative Example 3: While long-chain alkyl groups can provide some hydrophobicity, they lack the chemical stability and dense network of Si-O-Si bonds, resulting in insufficient chemical resistance.

[0059] In summary, the copolymers in Examples 4-6 provide a low surface energy surface layer, while the double crosslinked network enhances the hardness, abrasion resistance, and chemical resistance of the coating.

[0060] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fluorine-free water- and oil-repellent coating composition, characterized by comprising: The ingredients, by weight, include the following: 2-4 parts hydrogenated castor oil, 6-10 parts vinyltrimethoxysilane, 0.5-1 part photoinitiator, 0.1-0.5 parts leveling agent, 7-10 parts ethyl acetate, and 70-80 parts copolymer solution; The copolymer solution is a binary copolymer solution, wherein the first monomer is α-pinene and the second monomer is an acrylate monomer containing a long-chain alkyl group, with the general structural formula: CH2=C(R1)COOR2, where R1 is H or CH3 and R2 is a C8-C18 straight-chain or branched alkyl group. The copolymer solution is prepared by the following steps: α-Pinene was added to ethyl acetate, and the mixture was heated to 75-82°C under nitrogen protection. A mixture of acrylate containing long-chain alkyl groups and an initiator was added dropwise to the reaction system. After the addition was complete, the reaction was continued for 5-6 hours. After the reaction was completed, the mixture was cooled to below 40°C and filtered to obtain a copolymer solution. The mass ratio of α-pinene, ethyl acetate and acrylate containing long-chain alkyl groups is (68-70):(230-270):(102-118).

2. The coating composition according to claim 1, characterized in that, The photoinitiator is selected from at least one of photoinitiator 184, photoinitiator 1173, or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

3. The coating composition of claim 1, wherein, The leveling agent is selected from at least one of leveling agent 333, leveling agent 306, leveling agent 358 or leveling agent 361.

4. The coating composition of claim 1, wherein, The initiator is selected from at least one of azobisisobutyronitrile, benzoyl peroxide or azobisisoheptanenitrile, and the amount used is 0.8-1.2% of the total mass of α-pinene and acrylate containing long-chain alkyl groups.

5. A process for the preparation of a coating composition according to any one of claims 1 to 4, characterized in that Includes the following steps: S1. Mix hydrogenated castor oil and ethyl acetate, and stir for 15-20 minutes to obtain a pre-dispersed slurry; S2. Add copolymer solution, vinyltrimethoxysilane, photoinitiator and leveling agent to pre-dispersed slurry, stir for 20-30 minutes, mix evenly to obtain coating composition.

6. The production method according to claim 5, wherein The stirring speed in step S1 is 800-1000 rpm, and the stirring speed in step S2 is 400-600 rpm.

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