Preparation method of photocured organic silicon / siO2 super-hydrophobic coating with micro / nano papilla structure

Abstract

The application discloses a preparation method of a photocuring organic silicon / SiO2 super-hydrophobic coating with micro / nano papillary structure, and provides a strategy of combined application of an organic silicon polyurethane acrylate resin and modified nano-SiO2 in view of the environmental pollution and biological safety problems of organic fluorine materials; the modified nano-SiO2 particles are uniformly sprayed on the surface of the organic silicon polyurethane acrylate coating through a simple and low-cost spraying method; the modified nano-SiO2 is aggregated through an activation / inducer; and the bottom layer polymer is promoted to grow in situ upwards together with the nano-SiO2 particles to form a continuous and uniform micro / nano papillary structure through self-assembly. The micro / nano secondary rough surface with low surface energy endows the photocuring coating with excellent hydrophobic performance (water contact angle of 151 degrees and water sliding angle of 6 degrees) and anti-fouling (anti-graffiti) functions.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of super-hydrophobic coating processing, and particularly relates to a preparation method of a light-cured organic silicon / SiO2 super-hydrophobic coating with micro / nano papillary structure. BACKGROUND

[0002] Super-hydrophobic coating processing is a material surface modification technology, which forms a coating with special roughness and low surface energy on the material surface through the design of micro / nano structure and the composite application of low surface energy materials. The coating can significantly reduce the contact area of water, and realize the repulsion and rolling of water on the surface, with a contact angle (CA) generally greater than 150° and a rolling angle (SA) less than 10°. The excellent hydrophobic characteristics of the super-hydrophobic coating make it have the functions of self-cleaning, anti-fouling, anti-icing, anti-corrosion, etc., and it has been widely applied in many fields such as textile coating, building wall, steel surface coating, etc.

[0003] Currently, the preparation strategies for superhydrophobic coatings mainly include two parts: low surface energy material design and rough surface structure construction. Low surface energy material design refers to adding low surface energy materials to the coating material or introducing them into polymer segments to reduce the surface energy of the coating material, making it easier for water molecules to slide or roll off the coating surface, thus achieving its hydrophobic properties. Commonly used low surface energy materials include fluorinated compounds, organosilicon materials (siloxanes), fatty acids, and long-chain alkane compounds. The construction of micro / nano secondary rough surface structures is mainly achieved through methods such as template methods, sol-gel methods, etching methods, layer-by-layer self-assembly methods, and electrochemical deposition methods. Inspired by natural superhydrophobic surfaces such as lotus leaves, dragonfly wings, and water strider legs, constructing micro / nano secondary rough structures on the basis of low surface energy coatings can further improve the hydrophobic properties of the coating. Patent CN116764914A discloses a highly wear-resistant and highly transparent superhydrophobic nano-coating and its preparation method. This method uses a V-shaped nanoporous template to prepare a single nanoscale coating surface with a conical structure. Then, it chemically modifies the surface structure with liquid-like molecules possessing low surface energy and low friction coefficients to obtain a coating with superhydrophobic and self-cleaning properties. However, this method has limitations in template durability, and the separation process easily damages the microstructure of the hydrophobic surface, leading to a decrease in hydrophobicity. Patent CN117380505A discloses a functional superhydrophobic shape memory coating and its preparation method. This method first sandblasts the substrate material, then coats it with a coating material, and cures it by heating to obtain an initial coating. Next, the initial coating is photolithographically processed to obtain a coating with an array structure. Finally, a superhydrophobic shape memory coating is obtained by depositing silane compounds on the coating surface. Ye et al. (Applied Surface Science, 2023, 610:155362.) used electrochemical deposition and vapor deposition to combine robust electroplated nickel with excellent PDMS hydrophobic material to construct a superhydrophobic coating with multi-scale micro-nano structures on a copper substrate. This coating exhibits excellent mechanochemical stability, corrosion resistance, and self-cleaning properties. However, the equipment involved in the above methods is complex and expensive, and not suitable for mass production. Patent CN106479359A discloses an organosilicon superhydrophobic coating, its preparation method, and its application. This method uses a sol-gel method to form a micro-nano rough structure on the smooth surface of a base film through inter-hydroxyl condensation reaction. Subsequently, the organosilicon superhydrophobic coating is coated or sprayed onto the micro-nano rough surface of the base film, and after drying, an organosilicon superhydrophobic coating (water contact angle up to 158°, water roll-off angle less than 10°) is obtained. Patent CN116790185A discloses a method and application for constructing a superhydrophobic coating on a wood surface based on layer-by-layer self-assembly. The method involves sequentially coating the wood surface with component A and component B modification liquid under preset conditions, and then drying it at 160°C to complete the construction of a superhydrophobic coating on the wood surface.The superhydrophobic coating constructed by this method has a water contact angle as high as 163.1°. The prepared superhydrophobic wood exhibits excellent self-cleaning, abrasion resistance, and durability. However, the above method suffers from problems such as complex preparation processes and long processing times. CN109370408A discloses a method for preparing a superhydrophobic coating by combining waterborne polyurethane with hydrophobically modified inorganic nanoparticles. This method first sprays waterborne polyurethane onto a substrate, then heat-treats the polyurethane to semi-cur it, and then sprays a dispersion of hydrophobically modified inorganic nanoparticles onto the polyurethane film. After curing, a superhydrophobic coating with a micro / nano structure is obtained, achieving a water contact angle of up to 173.3°. CN113980576A discloses a method for preparing a durable superhydrophobic coating for anti-icing. This method first prepares a mixed solution of epoxy resin and silicone resin, as well as a composite suspension of nano- and submicron-sized silica particles. Then, the two solutions are mixed and heated to evaporate some of the solvent. A curing agent is added to obtain a superhydrophobic coating. Finally, the coating is sprayed onto the substrate surface, and after curing, a superhydrophobic coating with a micro-nano composite structure is obtained, achieving a surface contact angle greater than 150°, thus reaching a superhydrophobic state. However, the above methods all utilize the simple deposition of nanoparticles to construct micro-nano secondary rough surface structures, which easily leads to problems such as difficulty in controlling the structure and poor reproducibility. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a photocurable silicone / SiO2 superhydrophobic coating with a micro / nanopapillary structure. Addressing the environmental pollution and biosafety issues associated with organofluorine materials, this invention provides a strategy for the composite application of silicone polyurethane acrylate resin and modified nano-SiO2. A simple, low-cost spraying method is used to uniformly spray modified nano-SiO2 particles onto the surface of the silicone polyurethane acrylate coating. An activator / inducer is used to aggregate the modified nano-SiO2, promoting the in-situ upward growth of the underlying polymer, which self-assembles with the nano-SiO2 particles to form a continuous and uniform micro / nano "papillary" structure. This low-surface-energy, micro / nano secondary rough surface endows the photocurable coating with excellent hydrophobic properties (water contact angle of 151°, water slip angle of 6°) and anti-fouling (anti-graffiti) functions.

[0005] To solve the above technical problems, the following technical solution is adopted:

[0006] A method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures, characterized by comprising the following steps:

[0007] (1) A solution with specific surface tension, relative volatility, and solubility parameters is used as an activator / inducer. The activator / inducer, toughening agent, and modified nano-SiO2 are compounded to obtain a nano-SiO2 dispersion for constructing micro / nanopapillary structures. The dispersion contains the following components, which are in parts by weight:

[0008] 75-100 parts of activator / inducer

[0009] 10-25 parts toughening agent

[0010] 1-4 parts of modified nano-SiO2

[0011] (2) Preparation of an organosilicon polyurethane acrylate coating agent comprising an organosilicon polyurethane acrylate resin, the general structural formula of which is as follows:

[0012]

[0013] in,

[0014] R1 can be one or more of the following structures:

[0015]

[0016] Where R is the chain -CH2CH2CH2-, R' is -CH2CH2-, and n and m are the number of repeating units, 2-8;

[0017] (3) The modified nano-SiO2 dispersion was uniformly sprayed onto the surface of the uncured organosilicon polyurethane acrylate coating agent using a pneumatic spray gun, and then heated in an oven at 60°C for 10-15 seconds. After that, the coating film was irradiated by a light source for 2-4 minutes to complete the curing of the coating film, thus obtaining an organosilicon / SiO2 composite superhydrophobic coating with micro / nanoplasty structure.

[0018] After optimization, in step (1), the surface tension of the activator / inducer is 20-30 mN / m, the relative volatility is 1.2-3.1, and the solubility parameter is 11.4-14.4 (cal / cm³). 3 ) 1 / 2 It is composed of one or more of the following: anhydrous ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, and water.

[0019] After optimization, in step (1), the toughening agent is an acrylate monomer containing flexible segments, including one or a mixture of several of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methyl butyl acrylate, ethylene glycol dimethacrylate, 2-ethoxyethyl acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

[0020] After optimization, in step (1), the modified nano-SiO2 refers to nano-SiO2 with a surface grafted with a photosensitive silane coupling agent and a long alkane-based silane coupling agent; wherein, the photosensitive silane coupling agent is one or more of 3-(isobutenoyloxy)propyltrimethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-[dimethoxy(methyl)silyl]propyl methacrylate, vinyltrimethoxysilane, and allyltrimethoxysilane; the long alkane-based silane coupling agent is one or more of decyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, and trimethoxy(7-octen-1-yl)silane.

[0021] After optimization, in step (2), R2 is one or more of hexamethylene, tolyl, isophorone, 4,4'-dicyclohexylmethyl, diphenylmethane, m-phenylenedimethyl, and dicyclohexylmethyl; R3 is one or more of chain-CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2C(CH3)CH2-, and -CH2CH2N(CH3)CH2CH2-; R4 is one or more of 5-norbornen-2-methylamine, 5-norbornen-2-ol, 5-norbornen-2-carboxylic acid, 1-penten-3-ol, 3,6-nonadienol, 2,4-hexadien-1-ol, 4-pentenoic acid, 10-undecenoic acid, diallylamine, and octadecane-9,12-dienoic acid; and n is the number of repeating units, 3-7.

[0022] After optimization, in step (2), the silicone polyurethane acrylate coating agent comprises the following components, which are in parts by weight:

[0023] 60-90 parts of silicone polyurethane acrylate resin 10-40 parts of reactive diluent

[0024] 1 to 3 parts of photoinitiator.

[0025] Preferably, the reactive diluent is a hydrophobic acrylate monomer, comprising one or more of the following: isooctyl acrylate, butyl acrylate, methyl methacrylate, dodecyl 2-acrylate, lauryl methacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, octadecyl methacrylate, propoxylated trimethylolpropane triacrylate, and tricyclodecanediethanol diacrylate.

[0026] Preferably, the photoinitiator is one or more of the following: ethyl 2,4,6-trimethylbenzoylphosphonate, chlorothioxanthonone, 2-isopropylthioxanthonone, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-methyl-1-[4-methylthiophenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-phenyl ketone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methylphenylpropanone.

[0027] After optimization, in step (3), the nozzle diameter of the spray gun used for spraying is 0.3 to 0.5 mm, the spray gun pressure is 2 to 5 bar, and the distance between the spray gun and the coating surface is 10 to 15 cm.

[0028] After optimization, in step (3), the light source is an ultraviolet or blue LED light source with a maximum emission wavelength of 365nm to 475nm.

[0029] The above technical solution has the following beneficial effects:

[0030] 1. This invention provides a method for the large-scale preparation of photocurable silicone / SiO2 superhydrophobic coatings with micro / nanopapillary structures using a simple spraying method. Unlike the simple deposition method of conventional spraying, this method uses a spray gun to uniformly spray a modified nano-SiO2 dispersion onto the surface of a silicone polyurethane acrylate coating. Utilizing its activation and induction effects, the underlying polymer grows upwards in situ, self-assembling with the nano-SiO2 particles to form a continuous and uniform micro / nanopapillary structure, and this process can be achieved in large-scale preparation. The prepared photocurable superhydrophobic coating exhibits excellent hydrophobic properties (water contact angle of 151°, water slip angle of 6°) and anti-fouling (anti-graffiti) functions.

[0031] 2. The micro / nanopapillary structure constructed in this invention has good stability and durability. By using photosensitive silane coupling agents and long alkane-based silane coupling agents to modify the surface of nano-SiO2 particles, the hydrophobicity of nano-SiO2 and its dispersion stability in monomers and polyurethanes can be improved. On the other hand, by grafting double bond groups onto the surface of nano-SiO2, copolymerization of nano-SiO2, toughening agents and polymers can be achieved, thereby improving the stability of the micro / nano secondary structure. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings:

[0033] Figure 1 This is an optical photograph of the photocurable organosilicon / SiO2 superhydrophobic coating prepared in Example 1;

[0034] Figure 2 This is a SEM image of the photocurable organosilicon / SiO2 superhydrophobic coating prepared in Example 2;

[0035] Figure 3 The contact angle of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 3;

[0036] Figure 4 The roll-off angle of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 4;

[0037] Figure 5 These are digital photographs of different liquids on the surface of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 5;

[0038] Figure 6 This is a SEM image of the photocurable organosilicon / SiO2 coating prepared in Comparative Example 1;

[0039] Figure 7 This is an optical photograph of the photocurable organosilicon / SiO2 coating prepared in Comparative Example 2;

[0040] Figure 8 This is an optical photograph of the photocurable organosilicon / SiO2 coating prepared in Comparative Example 3;

[0041] Figure 9 This is the contact angle of the photocurable silicone / SiO2 coating prepared in Comparative Example 3. Detailed Implementation

[0042] This invention aims to provide a method for preparing a photocurable silicone / SiO2 superhydrophobic coating with a micro / nanopapillary structure. A simple and low-cost spraying method is used to uniformly spray modified nano-SiO2 particles onto the surface of a silicone polyurethane acrylate coating. An activator / inducer is used to aggregate the modified nano-SiO2, promoting the in-situ upward growth of the underlying polymer, which self-assembles with the nano-SiO2 particles to form a continuous and uniform micro / nanopapillary structure. This low-surface-energy, micro / nano-level rough surface endows the photocurable coating with excellent hydrophobic properties (water contact angle of 151°, water slip angle of 6°) and anti-fouling (anti-graffiti) functions.

[0043] The technical solution of the present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0044] Example 1

[0045] (1) Prepare a nano-SiO2 dispersion for constructing micro / nanopapillary structures. Its components are as follows:

[0046] Activator / Inducer: 50 parts anhydrous ethanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 27 parts water;

[0047] Toughening agents: 10 parts of hydroxyethyl acrylate (Aladdin reagent) and 10 parts of propoxylated trimethylolpropane triacrylate (Aladdin reagent);

[0048] Modified nano-SiO2: 3 parts were prepared in-house, in which the photosensitive silane coupling agent was 3-(isobutenoyloxy)propyltrimethoxysilane and the long alkane silane coupling agent was dodecyltrimethoxysilane.

[0049] The preparation steps of the self-made modified nano-SiO2 are as follows: First, weigh 5g of nano-SiO2 and add it to a wide-mouth bottle containing 300mL of anhydrous ethanol and water (4:1). Disperse it ultrasonically for 40min, then transfer it to a three-necked round-bottom flask and place it in a constant temperature water bath for uniform stirring. Adjust the pH of the solution to 10 with NaOH and HCl. After the stirring is stable, add 0.7g of photosensitive silane coupling agent and 0.3g of long alkane-based silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) through a dropper from the mouth of the bottle. React at 80℃ for 6-8h. After the reaction is completed, cool to room temperature and wash thoroughly with anhydrous ethanol and ultrapure water, respectively. Then dry in a vacuum drying oven at 80℃ for 12h and grind for later use to obtain modified nano-SiO2.

[0050] (2) Prepare the silicone polyurethane acrylate coating agent, the components of which are as follows:

[0051] Organosilicon polyurethane acrylate resin: 60 parts prepared in-house, wherein the organosilicon is hydroxyl-terminated organosilicon diol ~1000, the isocyanate is dicyclohexamethylene 4,4'-diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is octadecane-9,12-dienoic acid, and the repeating unit n=6.

[0052] Reactive diluents: 29 parts isooctyl acrylate (Aladdin reagent), 10 parts dodecyl 2-acrylate (Aladdin reagent);

[0053] Photoinitiator: 1 part of ethyl 2,4,6-trimethylbenzoylphosphonate (Aladdin reagent);

[0054] The method for synthesizing the self-made organosilicon polyurethane acrylate resin consists of the following three steps: First, under the protection of an inert gas, isocyanate and organosilicon diol are thoroughly mixed at a molar ratio of 2.2 to 3.0:1, and 40 ppm of triethylenediamine catalyst is added. The mixture is reacted at 80°C for 2 to 3 hours to obtain a reactive prepolymer. Second, 30 to 60% of the molar amount of isocyanate chain extender is added dropwise to the prepolymer from the previous step, and the mixture is reacted at 70°C for 2 to 3 hours to obtain a reactive intermediate. Third, 30 to 60% of the molar amount of isocyanate end-capping agent is added dropwise to the intermediate from the previous step, and the mixture is reacted at 65°C for 6 to 7 hours to obtain the product, organosilicon polyurethane acrylate resin.

[0055] (3) Using a pneumatic spray gun with a nozzle diameter of 0.3 to 0.5 mm, adjust the spray gun pressure to 2 to 5 bar, uniformly spray the modified nano-SiO2 dispersion onto the surface of the uncured organosilicon polyurethane acrylate coating agent, and place it in an oven at 60°C for 10 to 15 seconds. Then, irradiate it with ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film and obtain an organosilicon / SiO2 composite superhydrophobic coating with micro / nanopapillary structure.

[0056] Example 2

[0057] (1) Prepare a nano-SiO2 dispersion for constructing micro / nanopapillary structures. Its components are as follows:

[0058] Activator / Inducer: 30 parts methanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 25 parts anhydrous ethanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), and 21 parts water;

[0059] Toughening agents: 12 parts hydroxypropyl methacrylate (Aladdin reagent), 8 parts pentaerythritol triacrylate (Aladdin reagent);

[0060] Modified nano-SiO2: 4 parts were prepared in-house, of which the photosensitive silane coupling agent was 3-(isobutenoyloxy)propyltrimethoxysilane and the long alkane silane coupling agent was octadecyltrimethoxysilane.

[0061] The preparation steps of the self-made modified nano-SiO2 are as follows: First, weigh 5g of nano-SiO2 and add it to a wide-mouth bottle containing 300mL of anhydrous ethanol and water (4:1). Disperse it ultrasonically for 40min, then transfer it to a three-necked round-bottom flask and place it in a constant temperature water bath for uniform stirring. Adjust the pH of the solution to 10 with NaOH and HCl. After the stirring is stable, add 0.7g of photosensitive silane coupling agent and 0.3g of long alkane-based silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) through a dropper from the mouth of the bottle. React at 80℃ for 6-8h. After the reaction is completed, cool to room temperature and wash thoroughly with anhydrous ethanol and ultrapure water, respectively. Then dry in a vacuum drying oven at 80℃ for 12h and grind for later use to obtain modified nano-SiO2.

[0062] (2) Prepare the silicone polyurethane acrylate coating agent, the components of which are as follows:

[0063] Organosilicon polyurethane acrylate resin: 70 parts prepared in-house, wherein the organosilicon is a dihydroxy mono-terminated organosilicon diol ~1500, the isocyanate is isophorone diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 1-penten-3-ol, and the repeating unit n=5.

[0064] Reactive diluents: 20 parts butyl acrylate (Aladdin reagent), 9 parts tripropylene glycol diacrylate (Aladdin reagent);

[0065] Photoinitiators: 0.5 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Aladdin reagent) and 0.5 parts of 2-isopropylthioxanthone (Aladdin reagent);

[0066] The method for synthesizing the self-made organosilicon polyurethane acrylate resin consists of the following three steps: First, under the protection of an inert gas, isocyanate and organosilicon diol are thoroughly mixed at a molar ratio of 2.2 to 3.0:1, and 40 ppm of triethylenediamine catalyst is added. The mixture is reacted at 80°C for 2 to 3 hours to obtain a reactive prepolymer. Second, 30 to 60% of the molar amount of isocyanate chain extender is added dropwise to the prepolymer from the previous step, and the mixture is reacted at 70°C for 2 to 3 hours to obtain a reactive intermediate. Third, 30 to 60% of the molar amount of isocyanate end-capping agent is added dropwise to the intermediate from the previous step, and the mixture is reacted at 65°C for 6 to 7 hours to obtain the product, organosilicon polyurethane acrylate resin.

[0067] (3) Using a pneumatic spray gun with a nozzle diameter of 0.3 to 0.5 mm, adjust the spray gun pressure to 2 to 5 bar, uniformly spray the modified nano-SiO2 dispersion onto the surface of the uncured organosilicon polyurethane acrylate coating agent, and place it in an oven at 60°C for 10 to 15 seconds. Then, irradiate it with ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film and obtain an organosilicon / SiO2 composite superhydrophobic coating with micro / nanopapillary structure.

[0068] Example 3

[0069] (1) Prepare a nano-SiO2 dispersion for constructing micro / nanopapillary structures. Its components are as follows:

[0070] Activator / Inducer: 50 parts anhydrous ethanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 10 parts isopropanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), and 20 parts water;

[0071] Toughening agents: 12 parts methyl butyl acrylate (Aladdin reagent), 5 parts ethoxylated trimethylolpropane triacrylate (Aladdin reagent);

[0072] Modified nano-SiO2: 3 parts were prepared in-house, wherein the photosensitive silane coupling agent was 3-(acryloyloxy)propyltrimethoxysilane and the long alkane silane coupling agent was octadecyltrimethoxysilane;

[0073] The preparation steps of the self-made modified nano-SiO2 are as follows: First, weigh 5g of nano-SiO2 and add it to a wide-mouth bottle containing 300mL of anhydrous ethanol and water (4:1). Disperse it ultrasonically for 40min, then transfer it to a three-necked round-bottom flask and place it in a constant temperature water bath for uniform stirring. Adjust the pH of the solution to 10 with NaOH and HCl. After the stirring is stable, add 0.7g of photosensitive silane coupling agent and 0.3g of long alkane-based silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) through a dropper from the mouth of the bottle. React at 80℃ for 6-8h. After the reaction is completed, cool to room temperature and wash thoroughly with anhydrous ethanol and ultrapure water, respectively. Then dry in a vacuum drying oven at 80℃ for 12h and grind for later use to obtain modified nano-SiO2.

[0074] (2) Prepare the silicone polyurethane acrylate coating agent, the components of which are as follows:

[0075] Organosilicon polyurethane acrylate resin: 65 parts prepared in-house, wherein the organosilicon is hydroxyl-terminated organosilicon diol ~2000, the isocyanate is hexamethylene diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 10-undecenoic acid, and the repeating unit n=4.

[0076] Reactive diluents: 26 parts of isooctyl acrylate (Aladdin reagent) and 8 parts of propoxylated trimethylolpropane triacrylate (Aladdin reagent);

[0077] Photoinitiators: 0.4 parts of 1-[4-(phenylthio)phenyl]-1,2-octanedione, 2-(O-benzoyl oxime) (Aladdin reagent), and 0.6 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (Aladdin reagent);

[0078] The method for synthesizing the self-made organosilicon polyurethane acrylate resin consists of the following three steps: First, under the protection of an inert gas, isocyanate and organosilicon diol are thoroughly mixed at a molar ratio of 2.2 to 3.0:1, and 40 ppm of triethylenediamine catalyst is added. The mixture is reacted at 80°C for 2 to 3 hours to obtain a reactive prepolymer. Second, 30 to 60% of the molar amount of isocyanate chain extender is added dropwise to the prepolymer from the previous step, and the mixture is reacted at 70°C for 2 to 3 hours to obtain a reactive intermediate. Third, 30 to 60% of the molar amount of isocyanate end-capping agent is added dropwise to the intermediate from the previous step, and the mixture is reacted at 65°C for 6 to 7 hours to obtain the product, organosilicon polyurethane acrylate resin.

[0079] (3) Using a pneumatic spray gun with a nozzle diameter of 0.3 to 0.5 mm, adjust the spray gun pressure to 2 to 5 bar, uniformly spray the modified nano-SiO2 dispersion onto the surface of the uncured organosilicon polyurethane acrylate coating agent, and place it in an oven at 60°C for 10 to 15 seconds. Then, irradiate it with ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film and obtain an organosilicon / SiO2 composite superhydrophobic coating with micro / nanopapillary structure.

[0080] Example 4

[0081] (1) Prepare a nano-SiO2 dispersion for constructing micro / nanopapillary structures. Its components are as follows:

[0082] Activating / inducing agents: 45 parts anhydrous ethanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 30 parts methanol (Hangzhou Gaojing Fine Chemical Co., Ltd.);

[0083] Toughening agents: 14 parts of ethylene glycol dimethacrylate (Aladdin reagent) and 7 parts of propoxylated trimethylolpropane triacrylate (Aladdin reagent);

[0084] Modified nano-SiO2: 4 parts were prepared in-house, of which the photosensitive silane coupling agent was 3-[dimethoxy(methyl)silyl]propyl methacrylate and the long alkane silane coupling agent was hexadecyltrimethoxysilane;

[0085] The preparation steps of the self-made modified nano-SiO2 are as follows: First, weigh 5g of nano-SiO2 and add it to a wide-mouth bottle containing 300mL of anhydrous ethanol and water (4:1). Disperse it ultrasonically for 40min, then transfer it to a three-necked round-bottom flask and place it in a constant temperature water bath for uniform stirring. Adjust the pH of the solution to 10 with NaOH and HCl. After the stirring is stable, add 0.7g of photosensitive silane coupling agent and 0.3g of long alkane-based silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) through a dropper from the mouth of the bottle. React at 80℃ for 6-8h. After the reaction is completed, cool to room temperature and wash thoroughly with anhydrous ethanol and ultrapure water, respectively. Then dry in a vacuum drying oven at 80℃ for 12h and grind for later use to obtain modified nano-SiO2.

[0086] (2) Prepare the silicone polyurethane acrylate coating agent, the components of which are as follows:

[0087] Organosilicon polyurethane acrylate resin: 60 parts prepared in-house, wherein the organosilicon is hydroxyl-double-terminated organosilicon diol ~1000 and dihydroxyl-single-terminated organosilicon diol ~4500, the isocyanate is isophorone diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 5-norbornene-2-carboxylic acid, and the repeating unit n=5.

[0088] Reactive diluents: 27 parts of 1,6-hexanediol diacrylate (Aladdin reagent), 12 parts of octadecyl methacrylate (Aladdin reagent);

[0089] Photoinitiator: 0.6 parts of 2-hydroxy-2-methyl-1-phenyl ketone (Aladdin reagent), 0.4 parts of 1-hydroxycyclohexyl phenyl ketone (Aladdin reagent);

[0090] The method for synthesizing the self-made organosilicon polyurethane acrylate resin consists of the following three steps: First, under the protection of an inert gas, isocyanate and organosilicon diol are thoroughly mixed at a molar ratio of 2.2 to 3.0:1, and 40 ppm of triethylenediamine catalyst is added. The mixture is reacted at 80°C for 2 to 3 hours to obtain a reactive prepolymer. Second, 30 to 60% of the molar amount of isocyanate chain extender is added dropwise to the prepolymer from the previous step, and the mixture is reacted at 70°C for 2 to 3 hours to obtain a reactive intermediate. Third, 30 to 60% of the molar amount of isocyanate end-capping agent is added dropwise to the intermediate from the previous step, and the mixture is reacted at 65°C for 6 to 7 hours to obtain the product, organosilicon polyurethane acrylate resin.

[0091] (3) Using a pneumatic spray gun with a nozzle diameter of 0.3 to 0.5 mm, adjust the spray gun pressure to 2 to 5 bar, uniformly spray the modified nano-SiO2 dispersion onto the surface of the uncured organosilicon polyurethane acrylate coating agent, and place it in an oven at 60°C for 10 to 15 seconds. Then, irradiate it with ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film and obtain an organosilicon / SiO2 composite superhydrophobic coating with micro / nanopapillary structure.

[0092] Example 5

[0093] (1) Prepare a nano-SiO2 dispersion for constructing micro / nanopapillary structures. Its components are as follows:

[0094] Activator / Inducer: 55 parts methanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 20 parts water (Hangzhou Gaojing Fine Chemical Co., Ltd.);

[0095] Toughening agents: 16 parts methyl butyl acrylate (Aladdin reagent), 5 parts pentaerythritol tetraacrylate (Aladdin reagent);

[0096] Modified nano-SiO2: 4 parts were prepared in-house, in which the photosensitive silane coupling agent was vinyltrimethoxysilane and the long alkane silane coupling agent was decyltrimethoxysilane;

[0097] The preparation steps of the self-made modified nano-SiO2 are as follows: First, weigh 5g of nano-SiO2 and add it to a wide-mouth bottle containing 300mL of anhydrous ethanol and water (4:1). Disperse it ultrasonically for 40min, then transfer it to a three-necked round-bottom flask and place it in a constant temperature water bath for uniform stirring. Adjust the pH of the solution to 10 with NaOH and HCl. After the stirring is stable, add 0.7g of photosensitive silane coupling agent and 0.3g of long alkane-based silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) through a dropper from the mouth of the bottle. React at 80℃ for 6-8h. After the reaction is completed, cool to room temperature and wash thoroughly with anhydrous ethanol and ultrapure water, respectively. Then dry in a vacuum drying oven at 80℃ for 12h and grind for later use to obtain modified nano-SiO2.

[0098] (2) Prepare the silicone polyurethane acrylate coating agent, the components of which are as follows:

[0099] Organosilicon polyurethane acrylate resin: 65 parts prepared in-house, wherein the organosilicon is hydroxyl-terminated organosilicon diol ~2000 and dihydroxyl-terminated organosilicon diol ~1500, the isocyanate is isophorone diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 2,4-hexadien-1-ol, and the repeating unit n=6.

[0100] Reactive diluents: 22 parts of isooctyl acrylate (Aladdin reagent) and 12 parts of tricyclodecanediethanol diacrylate (Aladdin reagent);

[0101] Photoinitiator: ethyl 2,4,6-trimethylbenzoylphosphonate (Aladdin reagent) 0.6 parts, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (Aladdin reagent) 0.4 parts;

[0102] The method for synthesizing the self-made organosilicon polyurethane acrylate resin consists of the following three steps: First, under the protection of an inert gas, isocyanate and organosilicon diol are thoroughly mixed at a molar ratio of 2.2 to 3.0:1, and 40 ppm of triethylenediamine catalyst is added. The mixture is reacted at 80°C for 2 to 3 hours to obtain a reactive prepolymer. Second, 30 to 60% of the molar amount of isocyanate chain extender is added dropwise to the prepolymer from the previous step, and the mixture is reacted at 70°C for 2 to 3 hours to obtain a reactive intermediate. Third, 30 to 60% of the molar amount of isocyanate end-capping agent is added dropwise to the intermediate from the previous step, and the mixture is reacted at 65°C for 6 to 7 hours to obtain the product, organosilicon polyurethane acrylate resin.

[0103] (3) Using a pneumatic spray gun with a nozzle diameter of 0.3 to 0.5 mm, adjust the spray gun pressure to 2 to 5 bar, uniformly spray the modified nano-SiO2 dispersion onto the surface of the uncured organosilicon polyurethane acrylate coating agent, and place it in an oven at 60°C for 10 to 15 seconds. Then, irradiate it with ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film and obtain an organosilicon / SiO2 composite superhydrophobic coating with micro / nanopapillary structure.

[0104] Comparative Example 1

[0105] This comparative example is basically the same as Example 1, except that when preparing the nano-SiO2 dispersion for constructing micro / nanopapillary structures, the activator / inducer consists of 30 parts of anhydrous ethanol and 47 parts of water, thereby obtaining the nano-SiO2 dispersion.

[0106] Comparative Example 2

[0107] This comparative example is basically the same as Example 2, except that the nano-SiO2 used in the preparation of the nano-SiO2 dispersion for constructing micro / nanopapillary structures was not modified, thus obtaining the nano-SiO2 dispersion.

[0108] Comparative Example 3

[0109] This comparative example is basically the same as Example 3, except that the nano-SiO2 used in preparing the nano-SiO2 dispersion for constructing the micro / nanopapillary structure is a commercially available hydrophobic nano-SiO2. 2， This yields a nano-SiO2 dispersion.

[0110] Optical photographs of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 1 are shown below. Figure 1 The prepared coating surface exhibits a continuous and uniform papillary structure. It has been verified that the surface of the photocurable organosilicon / SiO2 superhydrophobic coatings prepared in Examples 1-5 all have a papillary structure.

[0111] The SEM image of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 2 is shown below. Figure 2 The prepared coating surface exhibits a continuous and uniform micron-sized papillary structure. Further magnification of the papillary structure reveals that it is composed of nano-sized SiO2 particles aggregated and cured by polymer bonding. It has been verified that the surface morphology of the photocurable silicone / SiO2 superhydrophobic coatings prepared in Examples 1-5 all possess micro / nanopapillary structures.

[0112] The contact angle of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 3 is shown in the figure. Figure 3 The water contact angle of the superhydrophobic coating is 153°. It has been verified that the photocurable silicone / SiO2 superhydrophobic coatings prepared in Examples 1-5 all have a water contact angle >150°.

[0113] The roll-off angle of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 4 is shown in [reference needed]. Figure 4 The water roll-off angle of the superhydrophobic coating is 6°. It has been verified that the photocurable silicone / SiO2 superhydrophobic coatings prepared in Examples 1-5 all have a water roll-off angle of <10°.

[0114] Digital photographs of different liquids on the surface of the photocurable silicone / SiO2 superhydrophobic coating prepared in Example 5 are shown below. Figure 5 The prepared superhydrophobic coatings have excellent antifouling properties. It has been verified that the photocurable silicone / SiO2 superhydrophobic coatings prepared in Examples 1-5 all have excellent antifouling properties.

[0115] SEM images of the photocurable silicone / SiO2 coating prepared in Comparative Example 1 are shown below. Figure 6 The coating surface exhibits an uneven and rough structure. This is because, compared to Example 1, the activator / inducer used in Comparative Example 1 has a higher surface tension, a lower relative volatility, and a higher solubility parameter. As a result, the droplets of the nano-SiO2 dispersion are difficult to penetrate into the uncured photocurable silicone polyurethane acrylate coating agent. During the curing process, it cannot play an activating and inducing role, and ultimately it is difficult for the underlying polymer to grow upward in situ and self-assemble with the nano-SiO2 particles to form a continuous and uniform micro / nano "papillary" structure.

[0116] Optical photographs of the photocurable silicone / SiO2 coating prepared in Comparative Example 2 are shown below. Figure 7The coating surface exhibits a morphology that is rough all over with tiny protrusions bonded together. This is because, compared to Example 2, the unmodified nano-SiO2 surface used in Comparative Example 2 has a large number of hydroxyl groups, which will form hydrogen bonds with oxygen atoms in the soft segment region of the PSUA coating, making it difficult for them to migrate and aggregate. During the curing process, due to the smaller number of aggregated particles, tiny protrusions are formed.

[0117] Optical photographs and contact angles of the photocurable silicone / SiO2 coating prepared in Comparative Example 3 are shown below. Figure 8 , Figure 9 The coating surface exhibits a blocky, rough structure composed of multiple protrusions bonded together. The contact angle of the coating is 140°. This is because, compared to Example 3, the commercially available hydrophobic nano-SiO2 used in Comparative Example 3 has a lower surface tension, making it prone to agglomeration and bonding together during the curing process. Therefore, the surface roughness of the coating is reduced, and the hydrophobicity decreases.

[0118] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures, characterized in that... Includes the following steps: (1) A solution with specific surface tension, relative volatility, and solubility parameters is used as an activator / inducer. The activator / inducer, toughening agent, and modified nano-SiO2 are compounded to obtain a nano-SiO2 dispersion for constructing micro / nanopapillary structures. The dispersion contains the following components, which are in parts by weight: 75-100 parts of activator / inducer 10-25 parts toughening agent 1-4 parts of modified nano-SiO2 The surface tension of the activator / inducer is 20–30 mN / m, the relative volatility is 1.2–3.1, and the solubility parameter is 11.4–14.4 (cal / cm³). 3 ) 1 / 2 It is composed of one or more of anhydrous ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, and water; Modified nano-SiO2 refers to nano-SiO2 with a surface grafted with a photosensitive silane coupling agent and a long alkane-based silane coupling agent; wherein, the photosensitive silane coupling agent is one or more of 3-(isobutenoyloxy)propyltrimethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-[dimethoxy(methyl)silyl]propyl methacrylate, vinyltrimethoxysilane, and allyltrimethoxysilane. (2) Preparation of an organosilicon polyurethane acrylate coating agent comprising an organosilicon polyurethane acrylate resin, the general structural formula of which is as follows: in, R1 can be one or more of the following structures: Where R is the chain -CH2CH2CH2-, R' is -CH2CH2-, and n and m are the number of repeating units, 2-8; R4 is 5-norbornene-2-methylamine, 5-norbornene-2-ol, 5-norbornene-2-carboxylic acid, or 1-pentene-3- One or more of the following: alcohols, 3,6-nonadienol, 2,4-hexadien-1-ol, 4-pentenoic acid, 10-undecenoic acid, diallylamine, and octadecane-9,12-dienoic acid; (3) The modified nano-SiO2 dispersion was uniformly sprayed onto the surface of the uncured organosilicon polyurethane acrylate coating agent using a pneumatic spray gun, and then heated in an oven at 60°C for 10-15 seconds. After that, the coating film was irradiated by a light source for 2-4 minutes to complete the curing of the coating film, thus obtaining an organosilicon / SiO2 composite superhydrophobic coating with micro / nanoplasty structure.

2. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures according to claim 1, characterized in that: In step (1), the toughening agent is an acrylate monomer containing flexible segments, including one or a mixture of several of the following: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methyl butyl acrylate, ethylene glycol dimethacrylate, 2-ethoxyethyl acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

3. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures according to claim 1, characterized in that: In step (1), the long alkyl silane coupling agent is one or more of decyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, and trimethoxy(7-octen-1-yl)silane.

4. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with a micro / nanopapillary structure according to claim 1, characterized in that: In step (2), R2 is one or more of hexamethylene, tolyl, isophorone, 4,4'-dicyclohexylmethyl, diphenylmethane, m-phenylenedimethyl, and dicyclohexylmethyl; R3 is one or more of chain-CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2C(CH3)CH2-, and -CH2CH2N(CH3)CH2CH2-; and n is the number of repeating units, 3-7.

5. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with a micro / nanopapillary structure according to claim 1, characterized in that: In step (2), the silicone polyurethane acrylate coating agent comprises the following components, which are in parts by weight: 60-90 parts of silicone polyurethane acrylate resin 10-40 parts of reactive diluent 1 to 3 parts of photoinitiator.

6. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures according to claim 5, characterized in that: The reactive diluent is a hydrophobic acrylate monomer, comprising one or more of the following: isooctyl acrylate, butyl acrylate, methyl methacrylate, dodecyl 2-acrylate, lauryl methacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, octadecyl methacrylate, propoxylated trimethylolpropane triacrylate, and tricyclodecanediethanol diacrylate.

7. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures according to claim 5, characterized in that: The photoinitiator is one or more of the following: ethyl 2,4,6-trimethylbenzoylphosphonate, chlorothioxanthonone, 2-isopropylthioxanthonone, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-methyl-1-[4-methylthiophenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-phenyl ketone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methylphenylpropanone.

8. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structure according to claim 1, characterized in that: In step (3), the nozzle diameter of the spray gun used for spraying is 0.3 to 0.5 mm, the spray gun pressure is 2 to 5 bar, and the distance between the spray gun and the coating surface is 10 to 15 cm.

9. The method for preparing a photocurable organosilicon / SiO2 superhydrophobic coating with micro / nanopapillary structures according to claim 1, characterized in that: In step (3), the light source is an ultraviolet or blue LED light source with a maximum emission wavelength of 365nm to 475nm.

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