Preparation method of photocuring organosilicon / SiO2 super-hydrophobic coating with micro / nano mastoid structure

Abstract

The invention discloses a preparation method of a light-cured organic silicon / SiO2 super-hydrophobic coating with a micro / nano mastoid structure, provides a strategy of composite application of organic silicon polyurethane acrylate resin and modified nano SiO2 aiming at the problems of environmental pollution and biological safety of an organic fluorine material, and provides a simple and low-cost spraying method, so that the light-cured organic silicon / SiO2 super-hydrophobic coating with a micro / nano mastoid structure can be prepared into a light-cured organic silicon / SiO2 super-hydrophobic coating with a micro / nano mastoid structure. The preparation method comprises the following steps: uniformly spraying modified nano SiO2 particles on the surface of an organic silicon polyurethane acrylate coating, aggregating the modified nano SiO2 through an activating / inducing agent, promoting in-situ upward growth of a bottom layer polymer, and self-assembling with the nano SiO2 particles to form a continuous and uniform micro / nano mastoid structure. The micro-nano secondary rough surface with low surface energy endows the photocuring coating with excellent hydrophobic performance (the water contact angle is 151 degrees, and the water sliding angle is 6 degrees) and an antifouling (anti-graffiti) function.

Description

Technical Field

[0001] The invention belongs to the field of super-hydrophobic coating processing, and in particular relates to a method for preparing a photocurable silicone / SiO2 super-hydrophobic coating with a micro / nanopapillary structure. Background Art

[0002] Superhydrophobic coating processing is a material surface modification technology. Through the design of micro-nano structures and the composite application of low surface energy materials, a coating with special roughness and low surface energy is formed on the surface of the material. This coating can significantly reduce the contact area of ​​water and achieve water repulsion and rolling on the surface. The contact angle (CA) is usually greater than 150°, and the rolling angle (SA) is less than 10°. The excellent hydrophobic properties of superhydrophobic coatings enable them to have functions such as self-cleaning, anti-fouling, anti-icing, and anti-corrosion. It has been widely used in many fields such as textile coatings, building walls, and steel surface coatings.

[0003] At present, the preparation strategy of super hydrophobic coating mainly includes two parts: low surface energy material design and rough surface structure construction. Among them, low surface energy material design refers to adding low surface energy material to coating material, or introducing it into polymer segment, so as to reduce the surface energy of coating material, make water molecules more easily slide or roll from coating surface, and realize its hydrophobic property. Commonly used low surface energy materials mainly include fluorine-containing compounds, organosilicon materials (siloxanes), fatty acids and long-chain alkane compounds. And the construction of micro-nano secondary rough surface structure is mainly realized by template method, sol-gel method, etching method, layer-by-layer self-assembly method, electrochemical deposition method, etc. Inspired by natural super hydrophobic surfaces such as lotus leaves, dragonfly wings, water strider legs, etc., constructing micro / nano secondary rough structure on the basis of low surface energy coating can further improve the hydrophobic property of coating. Patent CN116764914A discloses a highly wear-resistant and highly transparent super hydrophobic nano coating and its preparation method. The method uses a V-shaped nanopore template to prepare a single nanoscale and conical coating surface, and then chemically modifies the surface structure by liquid-like molecules with low surface energy and low friction coefficient to prepare a coating with super-hydrophobic and self-cleaning effects. However, the template has durability limitations in this method, and the separation process easily destroys the microstructure of the hydrophobic surface, resulting in a decrease in hydrophobicity. Patent CN117380505A discloses a functional super-hydrophobic shape memory coating and a preparation method thereof. The method first sandblasts the substrate material, and the coating is applied to the substrate material, and an initial coating is obtained by heating and curing, and then the initial coating is photolithographically processed to obtain a coating with an array structure, and finally a super-hydrophobic shape memory coating is obtained by deposition of silane compounds on the coating surface. Ye et al. (Applied Surface Science, 2023, 610: 155362.) Electrochemical deposition and vapor deposition are used to combine strong electroplated nickel with excellent PDMS hydrophobic materials, and a super hydrophobic coating with multi-scale micro-nano structure is constructed on a copper substrate, and the coating has excellent mechanochemical stability, corrosion resistance and self-cleaning performance. However, the equipment involved in the above method is complicated and expensive, and is not suitable for macro-processing. Patent CN106479359A discloses a kind of organosilicon super hydrophobic coating and its preparation method and application. The method adopts sol-gel method, and micro-nano rough structure is formed on the smooth surface of base film by condensation reaction between hydroxyl groups, and then organosilicon super hydrophobic coating is coated or sprayed on the micro-nano rough surface of base film, and organosilicon super hydrophobic coating is obtained after drying (water contact angle is up to 158 °, and water rolling angle is less than 10 °). Patent CN116790185A discloses a method and application of building super hydrophobic coating on wood surface based on self-assembly layer by layer. The method sequentially applies a component A modification liquid and a component B modification liquid on the wood surface according to preset conditions, and then dries the wood surface at 160° C. to complete the construction of a super-hydrophobic coating on the wood surface.The super-hydrophobic coating constructed by the method has a water contact angle of up to 163.1 °. The prepared super-hydrophobic wood has excellent self-cleaning, friction resistance and durability. However, the above method has problems such as complicated preparation process and long time consumption. CN109370408A discloses a method for preparing a super-hydrophobic coating by a composite of an aqueous polyurethane and hydrophobically modified inorganic nanoparticles. The method first sprays an aqueous polyurethane on a substrate, then semi-cures the polyurethane through thermal treatment, and then sprays a hydrophobically modified inorganic nanoparticle dispersion on a polyurethane film, and obtains a super-hydrophobic coating with a micro / nano structure after curing, and the water contact angle can reach 173.3 °. CN113980576A discloses a method for preparing a durable super-hydrophobic coating for anti-icing. The method first prepares a mixed solution of epoxy resin and silicone resin and a composite suspension of nano-scale and submicron-scale silica particles, then heats the two solutions and evaporates a portion of the solvent, adds a curing agent to obtain a super-hydrophobic coating, and finally sprays the coating onto the surface of the substrate. After curing, a super-hydrophobic coating with a micro-nano composite structure on the surface is obtained, and the surface contact angle is greater than 150°, reaching a super-hydrophobic state. However, the above methods all use simple deposition of nanoparticles to construct a micro-nano secondary rough surface structure, which is prone to problems such as difficult structure control and poor reproducibility. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a photocurable silicone / SiO2 super hydrophobic coating with a micro / nano papillary structure, and to provide a strategy for the composite application of silicone polyurethane acrylate resin and modified nano-SiO2 in view of the environmental pollution and biosafety problems of organic fluorine materials, wherein the modified nano-SiO2 particles are uniformly sprayed on the surface of the silicone polyurethane acrylate coating by a simple and low-cost spraying method, and the modified nano-SiO2 is aggregated by an activator / inducer, and the bottom polymer is prompted to grow upward in situ, and self-assembled with the nano-SiO2 particles to form a continuous and uniform micro / nano "papillar" structure. This micro-nano secondary rough surface with low surface energy gives the photocurable coating excellent hydrophobic properties (water contact angle of 151°, water sliding angle of 6°) and anti-fouling (anti-graffiti) functions.

[0005] In order to solve the above technical problems, the following technical solutions are adopted:

[0006] A method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapillary structure, characterized in that it comprises the following steps:

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

[0008] Activator / inducer 75-100 parts

[0009] Toughening agent 10-25 parts

[0010] Modified nano-SiO2 1-4 parts

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

[0012]

[0013] in,

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

[0015]

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

[0017] (3) The modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent using a pneumatic spray gun, and the coating film is cured by heating it in an oven at 60°C for 10 to 15 seconds and then irradiated with a light source for 2 to 4 minutes to obtain a silicone / SiO2 composite super-hydrophobic coating with a micro / nanopapillary structure.

[0018] Preferably, 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 / cm 3 ) 1 / 2 , is composed of one or more of anhydrous ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, water, etc.

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

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

[0021] Preferably, in the step (2), R2 is one or more of hexamethylene, tolyl, isophorone, 4,4'-dicyclohexylmethyl, diphenylmethane, meta-xylyl, 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-norbornene-2-methylamine, 5-norbornene-2-ol, 5-norbornene-2-carboxylic acid, 1-pentene-3-ol, 3,6-nonadienol, 2,4-hexadiene-1-ol, 4-pentenoic acid, 10-undecenoic acid, diallylamine, and octadecane-9,12-dienoic acid; and n is the number of repeating units, which is 3-7.

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

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

[0024] 1 to 3 parts of photoinitiator.

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

[0026] Preferably, the photoinitiator is one or more of ethyl 2,4,6-trimethylbenzoylphosphonate, chlorothioxanthone, 2-isopropylthioxanthone, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-phenylmethanone, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methylpropiophenone.

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

[0028] Preferably, 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. The present invention provides a method for preparing a photocurable silicone / SiO2 super-hydrophobic coating with a micro / nanopapillary structure in large quantities by a simple spraying method. Different from the simple deposition method of the conventional spraying method, the method uses a spray gun to evenly spray the modified nano-SiO2 dispersion on the surface of the silicone polyurethane acrylate coating, and uses its activation and induction to make the bottom polymer grow upward in situ, and self-assemble with nano-SiO2 particles to form a continuous and uniform micro / nano "papillary" structure, and can achieve macro-quantity preparation. The prepared photocurable super-hydrophobic coating has excellent hydrophobic properties (water contact angle of 151° and water sliding angle of 6°) and anti-fouling (anti-graffiti) function.

[0031] 2. The micro / nanopapillary structure constructed by the present invention has good stability and durability. By using photosensitive silane coupling agent and long alkyl silane coupling agent to modify the surface of nano-SiO2 particles, on the one hand, the hydrophobicity of nano-SiO2 and its dispersion stability in monomers and polyurethane can be improved; on the other hand, by grafting double bond groups to the surface of nano-SiO2, copolymerization of nano-SiO2, toughening agent and polymer can be achieved to improve the stability of the micro-nano secondary structure. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0035] Figure 3 is the contact angle of the photocurable silicone / SiO2 super-hydrophobic coating prepared in Example 3;

[0036] Figure 4 is the rolling angle of the photocurable silicone / SiO2 super-hydrophobic coating prepared in Example 4;

[0037] Figure 5 are digital photos of the surface of the photocurable silicone / SiO2 super-hydrophobic coating prepared in Example 5 with different liquids;

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

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

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

[0041] Fig. 9 is the contact angle of the photocurable silicone / SiO2 coating prepared in Comparative Example 3. DETAILED DESCRIPTION

[0042] The present invention aims to provide a method for preparing a photocurable silicone / SiO2 super hydrophobic coating with a micro / nano papillary structure, wherein modified nano-SiO2 particles are uniformly sprayed on the surface of a silicone polyurethane acrylate coating by a simple, low-cost spraying method, and the modified nano-SiO2 is aggregated by an activating / inducing agent, and the bottom polymer is prompted to grow upward in situ, and self-assembled with the nano-SiO2 particles to form a continuous, uniform micro / nano "papillar" structure. This micro-nano secondary rough surface with low surface energy gives the photocurable coating excellent hydrophobic properties (water contact angle of 151°, water sliding angle of 6°) and anti-fouling (anti-graffiti) functions.

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

[0044] Example 1

[0045] (1) A nano-SiO2 dispersion for constructing a micro / nanopapular structure is prepared, wherein the components are as follows:

[0046] Activation / inducing agent: 50 parts of anhydrous ethanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 27 parts of water;

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

[0048] Modified nano-SiO2: 3 parts of self-made, in which the photosensitive silane coupling agent is 3-(isobutylene acyloxy)propyltrimethoxysilane, and the long alkyl silane coupling agent is dodecyltrimethoxysilane;

[0049] Among them, the preparation steps of homemade 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), ultrasonically disperse it for 40 minutes, then transfer it to a three-necked round-bottom flask, put it into a constant temperature water bath and stir it at a uniform speed, adjust the pH of the solution to 10 with NaOH and HCl, and add 0.7g of photosensitive silane coupling agent and 0.3g of long alkyl silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) from the bottle mouth through a dropper after the stirring is stable, react at 80°C for 6 to 8h, cool to room temperature after the reaction is completed, and wash it thoroughly with anhydrous ethanol and ultrapure water respectively, then dry it in a vacuum drying oven at 80°C for 12h, grind it for use to obtain modified nano-SiO2.

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

[0051] Silicone polyurethane acrylate resin: 60 parts of self-made, wherein the silicone is hydroxyl di-terminated silicone diol ~1000, the isocyanate is dicyclohexylmethane 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] Active diluent: 29 parts of isooctyl acrylate (Aladdin reagent), 10 parts of 2-dodecyl acrylate (Aladdin reagent);

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

[0054] Among them, the synthesis method of the homemade silicone polyurethane acrylate resin is divided into the following three steps: the first step, under the protection of inert gas, isocyanate and silicone diol are fully mixed in a molar ratio of 2.2 to 3.0:1, and 40ppm of catalyst triethylenediamine is added, and the reaction is carried out at 80°C for 2 to 3 hours to obtain a reaction prepolymer; the second step, 30 to 60% of the molar number of isocyanate chain extender is added dropwise to the previous prepolymer, and the reaction is carried out at 70°C for 2 to 3 hours to obtain a reaction intermediate; the third step, 30 to 60% of the molar number of isocyanate end capping agent is added dropwise to the previous intermediate, and the reaction is carried out at 65°C for 6 to 7 hours to obtain the product silicone polyurethane acrylate resin.

[0055] (3) Using a pneumatic spray gun with a caliber of 0.3 to 0.5 mm and adjusting the spray gun pressure to 2 to 5 bar, the modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent, and the coating is placed in an oven at 60°C for heating for 10 to 15 seconds, followed by irradiation with an ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film to obtain a silicone / SiO2 composite super hydrophobic coating with a micro / nanopapillary structure.

[0056] Example 2

[0057] (1) A nano-SiO2 dispersion for constructing a micro / nanopapular structure is prepared, wherein the components are as follows:

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

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

[0060] Modified nano-SiO2: 4 parts of self-made, wherein the photosensitive silane coupling agent is 3-(isobutylene acyloxy)propyltrimethoxysilane, and the long alkyl silane coupling agent is octadecyltrimethoxysilane;

[0061] Among them, the preparation steps of homemade 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), ultrasonically disperse it for 40 minutes, then transfer it to a three-necked round-bottom flask, put it into a constant temperature water bath and stir it at a uniform speed, adjust the pH of the solution to 10 with NaOH and HCl, and add 0.7g of photosensitive silane coupling agent and 0.3g of long alkyl silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) from the bottle mouth through a dropper after the stirring is stable, react at 80°C for 6 to 8h, cool to room temperature after the reaction is completed, and wash it thoroughly with anhydrous ethanol and ultrapure water respectively, then dry it in a vacuum drying oven at 80°C for 12h, grind it for use to obtain modified nano-SiO2.

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

[0063] Silicone polyurethane acrylate resin: 70 parts of self-made, wherein the silicone is dihydroxy mono-terminated silicone diol ~1500, the isocyanate is isophorone diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 1-pentene-3-ol, and the repeating unit n=5;

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

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

[0066] Among them, the synthesis method of the homemade silicone polyurethane acrylate resin is divided into the following three steps: the first step, under the protection of inert gas, isocyanate and silicone diol are fully mixed in a molar ratio of 2.2 to 3.0:1, and 40ppm of catalyst triethylenediamine is added, and the reaction is carried out at 80°C for 2 to 3 hours to obtain a reaction prepolymer; the second step, 30 to 60% of the molar number of isocyanate chain extender is added dropwise to the previous prepolymer, and the reaction is carried out at 70°C for 2 to 3 hours to obtain a reaction intermediate; the third step, 30 to 60% of the molar number of isocyanate end capping agent is added dropwise to the previous intermediate, and the reaction is carried out at 65°C for 6 to 7 hours to obtain the product silicone polyurethane acrylate resin.

[0067] (3) Using a pneumatic spray gun with a caliber of 0.3 to 0.5 mm and adjusting the spray gun pressure to 2 to 5 bar, the modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent, and the coating is placed in an oven at 60°C for heating for 10 to 15 seconds, followed by irradiation with an ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film to obtain a silicone / SiO2 composite super hydrophobic coating with a micro / nanopapillary structure.

[0068] Example 3

[0069] (1) A nano-SiO2 dispersion for constructing a micro / nanopapular structure is prepared, wherein the components are as follows:

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

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

[0072] Modified nano-SiO2: 3 parts of self-made, in which the photosensitive silane coupling agent is 3-(acryloxy)propyltrimethoxysilane and the long alkyl silane coupling agent is octadecyltrimethoxysilane;

[0073] Among them, the preparation steps of homemade 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), ultrasonically disperse it for 40 minutes, then transfer it to a three-necked round-bottom flask, put it into a constant temperature water bath and stir it at a uniform speed, adjust the pH of the solution to 10 with NaOH and HCl, and add 0.7g of photosensitive silane coupling agent and 0.3g of long alkyl silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) from the bottle mouth through a dropper after the stirring is stable, react at 80°C for 6 to 8h, cool to room temperature after the reaction is completed, and wash it thoroughly with anhydrous ethanol and ultrapure water respectively, then dry it in a vacuum drying oven at 80°C for 12h, grind it for use to obtain modified nano-SiO2.

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

[0075] Silicone polyurethane acrylate resin: 65 parts of self-made, wherein the silicone is hydroxyl di-terminated silicone 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 diluent: 26 parts of isooctyl acrylate (Aladdin reagent), 8 parts of propoxylated trimethylolpropane triacrylate (Aladdin reagent);

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

[0078] Among them, the synthesis method of the homemade silicone polyurethane acrylate resin is divided into the following three steps: the first step, under the protection of inert gas, isocyanate and silicone diol are fully mixed in a molar ratio of 2.2 to 3.0:1, and 40ppm of catalyst triethylenediamine is added, and the reaction is carried out at 80°C for 2 to 3 hours to obtain a reaction prepolymer; the second step, 30 to 60% of the molar number of isocyanate chain extender is added dropwise to the previous prepolymer, and the reaction is carried out at 70°C for 2 to 3 hours to obtain a reaction intermediate; the third step, 30 to 60% of the molar number of isocyanate end capping agent is added dropwise to the previous intermediate, and the reaction is carried out at 65°C for 6 to 7 hours to obtain the product silicone polyurethane acrylate resin.

[0079] (3) Using a pneumatic spray gun with a caliber of 0.3 to 0.5 mm and adjusting the spray gun pressure to 2 to 5 bar, the modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent, and the coating is placed in an oven at 60°C for heating for 10 to 15 seconds, followed by irradiation with an ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film to obtain a silicone / SiO2 composite super hydrophobic coating with a micro / nanopapillary structure.

[0080] Example 4

[0081] (1) A nano-SiO2 dispersion for constructing a micro / nanopapular structure is prepared, wherein the components are as follows:

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

[0083] Toughener: 14 parts of ethylene glycol dimethacrylate (Aladdin reagent), 7 parts of propoxylated trimethylolpropane triacrylate (Aladdin reagent);

[0084] Modified nano-SiO2: 4 parts of self-made, wherein the photosensitive silane coupling agent is 3-[dimethoxy(methyl)silyl]propyl methacrylate, and the long alkyl silane coupling agent is hexadecyltrimethoxysilane;

[0085] Among them, the preparation steps of homemade 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), ultrasonically disperse it for 40 minutes, then transfer it to a three-necked round-bottom flask, put it into a constant temperature water bath and stir it at a uniform speed, adjust the pH of the solution to 10 with NaOH and HCl, and add 0.7g of photosensitive silane coupling agent and 0.3g of long alkyl silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) from the bottle mouth through a dropper after the stirring is stable, react at 80°C for 6 to 8h, cool to room temperature after the reaction is completed, and wash it thoroughly with anhydrous ethanol and ultrapure water respectively, then dry it in a vacuum drying oven at 80°C for 12h, grind it for use to obtain modified nano-SiO2.

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

[0087] Silicone polyurethane acrylate resin: 60 parts of self-made, wherein the silicone is hydroxyl di-terminated silicone diol ~1000 and dihydroxy mono-terminated silicone 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 diluent: 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] Among them, the synthesis method of the homemade silicone polyurethane acrylate resin is divided into the following three steps: the first step, under the protection of inert gas, isocyanate and silicone diol are fully mixed in a molar ratio of 2.2 to 3.0:1, and 40ppm of catalyst triethylenediamine is added, and the reaction is carried out at 80°C for 2 to 3 hours to obtain a reaction prepolymer; the second step, 30 to 60% of the molar number of isocyanate chain extender is added dropwise to the previous prepolymer, and the reaction is carried out at 70°C for 2 to 3 hours to obtain a reaction intermediate; the third step, 30 to 60% of the molar number of isocyanate end capping agent is added dropwise to the previous intermediate, and the reaction is carried out at 65°C for 6 to 7 hours to obtain the product silicone polyurethane acrylate resin.

[0091] (3) Using a pneumatic spray gun with a caliber of 0.3 to 0.5 mm and adjusting the spray gun pressure to 2 to 5 bar, the modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent, and the coating is placed in an oven at 60°C for heating for 10 to 15 seconds, followed by irradiation with an ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film to obtain a silicone / SiO2 composite super hydrophobic coating with a micro / nanopapillary structure.

[0092] Example 5

[0093] (1) A nano-SiO2 dispersion for constructing a micro / nanopapular structure is prepared, wherein the components are as follows:

[0094] Activation / induction agent: 55 parts of methanol (Hangzhou Gaojing Fine Chemical Co., Ltd.), 20 parts of water (Hangzhou Gaojing Fine Chemical Co., Ltd.);

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

[0096] Modified nano-SiO2: 4 parts of self-made, in which the photosensitive silane coupling agent is vinyl trimethoxy silane and the long alkyl silane coupling agent is decyl trimethoxy silane;

[0097] Among them, the preparation steps of homemade 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), ultrasonically disperse it for 40 minutes, then transfer it to a three-necked round-bottom flask, put it into a constant temperature water bath and stir it at a uniform speed, adjust the pH of the solution to 10 with NaOH and HCl, and add 0.7g of photosensitive silane coupling agent and 0.3g of long alkyl silane coupling agent (the modifier is dissolved in a certain amount of anhydrous ethanol) from the bottle mouth through a dropper after the stirring is stable, react at 80°C for 6 to 8h, cool to room temperature after the reaction is completed, and wash it thoroughly with anhydrous ethanol and ultrapure water respectively, then dry it in a vacuum drying oven at 80°C for 12h, grind it for use to obtain modified nano-SiO2.

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

[0099] Silicone polyurethane acrylate resin: 65 parts of self-made, wherein the silicone is hydroxyl di-terminated silicone diol ~2000 and dihydroxy mono-terminated silicone diol ~1500, the isocyanate is isophorone diisocyanate, the chain extender is 1,4-butanediol, the end-capping agent is 2,4-hexadiene-1-ol, and the repeating unit n=6;

[0100] Reactive diluent: 22 parts of isooctyl acrylate (Aladdin reagent), 12 parts of tricyclodecane dimethanol diacrylate (Aladdin reagent);

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

[0102] Among them, the synthesis method of the homemade silicone polyurethane acrylate resin is divided into the following three steps: the first step, under the protection of inert gas, isocyanate and silicone diol are fully mixed in a molar ratio of 2.2 to 3.0:1, and 40ppm of catalyst triethylenediamine is added, and the reaction is carried out at 80°C for 2 to 3 hours to obtain a reaction prepolymer; the second step, 30 to 60% of the molar number of isocyanate chain extender is added dropwise to the previous prepolymer, and the reaction is carried out at 70°C for 2 to 3 hours to obtain a reaction intermediate; the third step, 30 to 60% of the molar number of isocyanate end capping agent is added dropwise to the previous intermediate, and the reaction is carried out at 65°C for 6 to 7 hours to obtain the product silicone polyurethane acrylate resin.

[0103] (3) Using a pneumatic spray gun with a caliber of 0.3 to 0.5 mm and adjusting the spray gun pressure to 2 to 5 bar, the modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent, and the coating is placed in an oven at 60°C for heating for 10 to 15 seconds, followed by irradiation with an ultraviolet or blue LED light source for 2 to 4 minutes to complete the curing of the coating film to obtain a silicone / SiO2 composite super hydrophobic coating with a micro / nanopapillary structure.

[0104] Comparative Example 1

[0105] This comparative example is basically the same as the embodiment 1, except that when preparing the nano-SiO2 dispersion for constructing the micro / nanopapillary structure, the components of the activator / inducer are 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 the embodiment 2, except that when preparing the nano-SiO2 dispersion for constructing the micro / nanopapillary structure, the nano-SiO2 used is not modified, thereby obtaining the nano-SiO2 dispersion.

[0108] Comparative Example 3

[0109] This comparative example is basically the same as the embodiment 3, except that the nano-SiO2 used in the preparation of the nano-SiO2 dispersion for constructing the micro / nanopapillary structure is a commercial hydrophobic nano-SiO2. 2， Thus, a nano-SiO2 dispersion is obtained.

[0110] The optical photograph of the photocurable silicone / SiO2 super hydrophobic coating prepared in Example 1 is shown in Figure 1 The surface of the prepared coating presents a continuous and uniform papillary structure. It has been verified that the surfaces of the photocurable silicone / SiO2 super-hydrophobic coatings prepared in Examples 1-5 all have a papillary structure.

[0111] The SEM image of the photocurable silicone / SiO2 super hydrophobic coating prepared in Example 2 is shown in Figure 2 , the surface of the prepared coating presents a continuous and uniform micron-scale papillary structure. Further magnifying the papillary structure, it can be observed that the papillary structure is formed by the aggregation of nano-scale SiO2 particle primitives and is bonded and solidified by polymer. It has been verified that the surface morphology of the photocurable silicone / SiO2 super-hydrophobic coating prepared in Examples 1-5 all has a micro / nanopapillary structure.

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

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

[0114] Digital photos of the surface of the photocurable silicone / SiO2 super-hydrophobic coating prepared in Example 5 with different liquids are shown in Figure 5 The prepared super-hydrophobic coating has excellent anti-fouling performance. It has been verified that the photocurable silicone / SiO2 super-hydrophobic coatings prepared in Examples 1-5 all have excellent anti-fouling performance.

[0115] The SEM image of the photocurable silicone / SiO2 coating prepared in Comparative Example 1 is shown in Figure 6 The coating surface presents an uneven rough structure. This is because compared with Example 1, the activating / inducing agent used in Comparative Example 1 has a higher surface tension, a lower relative volatility and a higher solubility parameter, which makes it difficult for the droplets of the nano-SiO2 dispersion to penetrate into the uncured light-cured silicone polyurethane acrylate coating agent, and cannot play an activating and inducing role during the curing process. Ultimately, it is difficult for the bottom 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] The optical photograph of the photocurable silicone / SiO2 coating prepared in Comparative Example 2 is shown in Figure 7The coating surface presents a morphology of a whole surface with rough surface and tiny protrusions. This is because compared with Example 2, the surface of the unmodified nano-SiO2 used in Comparative Example 2 has a large number of hydroxyl groups, which will form hydrogen bonds with the oxygen atoms in the soft segment area of ​​the PSUA coating, making it difficult to migrate and aggregate. During the curing process, small protrusions are formed due to the small number of aggregated particles;

[0117] The optical photograph and contact angle of the photocurable silicone / SiO2 coating prepared in Comparative Example 3 are shown in Figure 8 , Fig. 9 The coating surface presents a block-like rough structure with multiple protrusions bonded together, and the contact angle of the coating is 140°. This is because the commercial hydrophobic nano-SiO2 used in Comparative Example 3 has a lower surface tension than that in Example 3, and is prone to agglomeration, and is bonded into blocks during the curing process. Therefore, the roughness of the coating surface is reduced, and the hydrophobicity is reduced.

[0118] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. A method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapillary structure, characterized in that The steps include: (1) A solution having specific surface tension, relative volatility and solubility parameters is used as an activator / inducer, and the activator / inducer, a toughening agent and modified nano-SiO2 are compounded to obtain a nano-SiO2 dispersion for constructing a micro / nanopapular structure; the dispersion comprises the following components, which are measured in parts by weight: Activator / inducer 75-100 parts Toughening agent 10-25 parts Modified nano-SiO2 1-4 parts (2) preparing an organosilicon polyurethane acrylate coating agent, comprising an organosilicon polyurethane acrylate resin, wherein the general structural formula of the organosilicon polyurethane acrylate resin is as follows: in, R1 is one or more of the following structures: Where R is the chain -CH2CH2CH2-, R' is -CH2CH2-, n and m are the number of repeating units 2-8; (3) The modified nano-SiO2 dispersion is evenly sprayed on the surface of the uncured silicone polyurethane acrylate coating agent using a pneumatic spray gun, and the coating film is cured by heating it in an oven at 60°C for 10 to 15 seconds and then irradiated with a light source for 2 to 4 minutes to obtain a silicone / SiO2 composite super-hydrophobic coating with a micro / nanopapillary structure.

2. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the 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 / cm 3 ) 1 / 2 , is composed of one or more of anhydrous ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, water, etc.

3. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the step (1), the toughening agent is an acrylate monomer containing a flexible segment, including one or a mixture of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, butyl methyl acrylate, ethylene glycol dimethacrylate, 2-ethoxyethyl acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

4. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapillary structure according to claim 1, characterized in that: In the step (1), the modified nano-SiO2 refers to nano-SiO2 whose surface is grafted with a photosensitive silane coupling agent and a long alkyl silane coupling agent; wherein the photosensitive silane coupling agent is one or more of 3-(isomethacryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-[dimethoxy(methyl)silyl]propyl methacrylate, vinyltrimethoxysilane, and allyltrimethoxysilane; and the long alkyl silane coupling agent is one or more of decyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, and trimethoxy(7-octen-1-yl)silane.

5. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the step (2), R2 is one or more of hexamethylene, tolyl, isophorone, 4,4'-dicyclohexylmethyl, diphenylmethane, meta-xylene dimethyl, 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-norbornene-2-methylamine, 5-norbornene-2-ol, 5-norbornene-2-carboxylic acid, 1-pentene-3-ol, 3,6-nonadienol, 2,4-hexadiene-1-ol, 4-pentenoic acid, 10-undecenoic acid, diallylamine, and octadecane-9,12-dienoic acid; and n is the number of repeating units, which is 3-7.

6. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the step (2), the silicone polyurethane acrylate coating agent comprises the following components, which are measured in parts by weight: 60-90 parts of silicone polyurethane acrylate resin Active diluent 10-40 parts 1 to 3 parts of photoinitiator.

7. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 6, characterized in that: The active diluent is a hydrophobic acrylate monomer, including one or more of isooctyl acrylate, butyl acrylate, methyl methacrylate, 2-dodecyl acrylate, lauryl methacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, octadecyl methacrylate, propoxylated trimethylolpropane triacrylate, and tricyclodecane dimethanol diacrylate.

8. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 6, characterized in that: The photoinitiator is one or more of ethyl 2,4,6-trimethylbenzoylphosphonate, chlorothioxanthone, 2-isopropylthioxanthone, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-methyl-1-[4-methylthiophenyl]-2-morpholinyl-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-phenylmethanone, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methylpropiophenone.

9. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the step (3), the caliber of the spray gun used for spraying is 0.3-0.5 mm, the pressure of the spray gun is 2-5 bar, and the distance between the spray gun and the coating surface is 10-15 cm.

10. The method for preparing a photocurable silicone / SiO2 super-hydrophobic coating having a micro / nanopapular structure according to claim 1, characterized in that: In the step (3), the light source is an ultraviolet or blue light LED light source with a maximum emission wavelength of 365nm to 475nm.

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