A marine environment stable super-hydrophobic surface and a preparation method thereof

Abstract

The application belongs to the technical field of coating materials, and particularly relates to a marine environment stable super-hydrophobic surface and a preparation method thereof. The super-hydrophobic surface is composed of a coating and a coating modifier. The coating is a two-component coating, which comprises an epoxy resin mixture and a curing agent. The coating modifier is composed of a solvent and a solute. The preparation method of the super-hydrophobic surface comprises the following steps: (1) preparing the coating modifier, (2) preparing fluorosilane modified silica, (3) preparing the epoxy resin mixture, and (4) preparing the super-hydrophobic surface. The super-hydrophobic surface is prepared by using the epoxy resin as a film-forming material, adding hydrophobically modified micron-sized silica and nano-sized silica to form a rough structure, and treating the coating with the coating modifier containing fluorosilane in the semi-cured stage of the coating. The hydroxyl groups react with the fluorosilane to graft the fluorosilane on the surface of the coating, effectively reducing the surface energy of the coating, and further imparting the super-hydrophobicity of the coating from two aspects of the rough structure and the low surface energy material.

Description

Technical fields:

[0001] This invention belongs to the field of coating materials technology, specifically relating to a superhydrophobic surface that is stable in marine environments and its preparation method, which is applicable to marine vehicles. Background technology:

[0002] A superhydrophobic surface is defined as a solid surface with a static contact angle (WCA) of not less than 150° and a roll-off angle (SA) of not more than 10° with a water droplet. Superhydrophobic properties are typically achieved through the synergistic effect of a rough surface structure and low surface energy materials. In existing technologies, there are generally two approaches to preparing superhydrophobic surfaces: (1) reducing the free energy of a rough solid surface; and (2) roughening a solid surface with low surface free energy. Specifically, common methods for preparing superhydrophobic surfaces include etching, template methods, organic-inorganic hybrid methods, and deposition methods.

[0003] Chinese Patent 201711046510.2 discloses a one-step method for preparing aluminum-based superhydrophobic surfaces. The specific steps are as follows: Prepare an aqueous solution of sodium chloride and an ethanol solution of perfluorotetradecanoic acid. Mix the two solutions and pour them into a hydrothermal reactor. Control the temperature at 150-180℃. Then, place a pure aluminum sheet that has been sanded and ultrasonically cleaned into the hydrothermal reactor. After sealing, place the hydrothermal reactor in a constant temperature chamber. After reacting for a period of time, remove the aluminum sheet, clean and dry it to obtain an aluminum-based superhydrophobic surface with a micro-nano structure. Alternatively, an etching technique can be used to prepare a superhydrophobic aluminum alloy surface. An aqueous solution of sodium chloride and an ethanol solution of perfluorotetradecanoic acid are placed together with an aluminum alloy plate in a high-temperature reactor. A rough structure is constructed on the aluminum alloy surface by water and sodium chloride, and the surface energy is reduced by perfluorotetradecanoic acid ethanol. Chinese Patent 201910055044.7 discloses a method for preparing a superhydrophobic surface of a PDMS-based biomimetic shark skin replica. The method includes: first, shark skin pretreatment; second, PDMS shark skin casting; third, treating the surface with the shark skin reverse structure using a plasma treatment machine for 20 seconds; fourth, PDMS casting according to the method in step two; and fifth, superhydrophobic treatment of the PDMS biomimetic shark skin replica. This method uses a PDMS two-stage casting technique to obtain a shark skin replica with a micron-level groove structure, and then subjectes the replica surface to combustion and oven heating treatments to obtain a surface with superhydrophobic properties. Chinese Patent 201711328539.X discloses a method for preparing a superhydrophobic microstructure anti-icing surface on the surface of a resin-based composite material, comprising the following steps: 1) using a resin-based composite material as the matrix material, first performing appropriate pretreatment to obtain a clean sample surface to be treated; 2) heating the resin-based composite material matrix to a certain temperature, and using an alumina template with a regular porous structure to mold it, so that a regular micro-pillar structure appears on its surface; 3) curing the resin-based composite material with a micro-pillar structure obtained in step 2), and slowly cooling it to room temperature; 4) immersing the cured resin-based composite material with a regular micro-pillar structure obtained in step 3) in an acetic acid solution, taking it out and drying it, and then immersing it in a stearic acid solution, taking it out and drying it to obtain a superhydrophobic surface of a resin-based composite material with a regular array; it first uses an alumina template with a regular porous structure to mold the resin matrix with a roller to form a microstructure on the surface of the resin matrix, then cures the resin and immerses it in a stearic acid solution, and then dries it to obtain a superhydrophobic resin. Chinese Patent 202010830891.9 discloses a method for preparing a water-based self-healing superhydrophobic coating, which includes the following steps: (1) preparing an organic-inorganic hybrid emulsifier, (2) preparing an organic-inorganic hybrid microcapsule, and (3) preparing a coating. The superhydrophobic surface is prepared by organic-inorganic hybrid technology. Multi-scale nanofiber particles, pore-forming agents, aqueous polymer emulsions and microcapsules are dispersed together in distilled water, mixed evenly and coated onto a glass plate. After drying, a superhydrophobic coating is obtained.Chinese Patent 202010680069.9 discloses a method for rapidly constructing a superhydrophobic / superoleophilic oil-water separation material, comprising the following specific steps: S1. Placing a high-temperature resistant mesh above a candle flame, depositing a layer of soot on its surface, and then placing it in a closed environment containing volatilized silicon compounds for vapor deposition to obtain a high-temperature resistant mesh with a silicon dioxide layer deposited on the outer surface of the soot layer; S2. Calcining the high-temperature resistant mesh obtained in step S1 at 500-1500℃ to remove soot particles, obtaining a high-temperature resistant mesh containing a silicon dioxide outer shell layer; S3. Hydrophobically modifying the high-temperature resistant mesh containing the silicon dioxide outer shell layer with organosilicon to obtain a superhydrophobic / superoleophilic oil-water separation material; the superhydrophobic surface is prepared by deposition, and after depositing soot on the high-temperature resistant mesh, it is placed in a closed environment containing volatilized silicon compounds for vapor deposition, and then calcined at high temperature to obtain a high-temperature resistant superhydrophobic surface.

[0004] The aforementioned patent describes a method for preparing superhydrophobic surfaces on different substrates, but it is only applicable to specific substrates and cannot maintain the superhydrophobic state for a long time in a seawater environment, limiting its application on the surfaces of marine vehicles. Since marine vehicles are typically coated with paint, preparing superhydrophobic coating materials would be a simpler and more widely applicable approach.

[0005] Epoxy resins are known for their excellent adhesion, mechanical properties, and outstanding chemical stability, and are widely used in various fields such as coatings, adhesives, fiber-reinforced materials, structural materials, and encapsulation materials. By modifying the epoxy resin system to have a rough structure and low surface energy, it is possible to achieve superhydrophobic coatings, making its application in marine environments more practical. Summary of the Invention:

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and to develop and design a marine environment-stable superhydrophobic surface and its preparation method, so that the epoxy coating has superhydrophobicity in both rough structure and low surface energy material.

[0007] To achieve the above objectives, the marine environment-stable superhydrophobic surface of the present invention comprises a coating and a coating modifier;

[0008] The coating is a two-component coating, and the components and their proportions by mass percentage are: epoxy resin mixture 75-80%, curing agent 20-25%;

[0009] The components and proportions of the epoxy resin mixture by mass percentage are: epoxy resin 30-50%, fluorosilane-modified silica 40-60%, and xylene 5-30%.

[0010] Epoxy resins include, but are not limited to, E44 epoxy resin, E51 epoxy resin, EF epoxy resin and fluorosilane-modified epoxy resins;

[0011] In the silica used in fluorosilane-modified silica, the mass percentage of micron-sized silica is 40-90%, and the mass percentage of nano-sized silica is 10-60%.

[0012] The curing agent is an aliphatic curing agent, including ethylenediamine, polyetheramine and polyamide.

[0013] The coating modifier consists of a solvent and a solute, and the components and their proportions by volume percentage are: solute 90-99%, solvent 1-10%;

[0014] Solvents include, but are not limited to, organic solvents such as n-hexane, toluene, and ethyl acetate;

[0015] The solute includes, but is not limited to, 1H, 1H, 2H, 2H-perfluorooctylmethyldichlorosilane.

[0016] 1H, 1H, 2H, 2H-perfluorooctyltrichlorosilane, 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane, 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane, 1H, 1H,

[0017] 2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 1H,1H,

[0018] Fluorosilane coupling agents such as 2H,2H-perfluorodecyltriethoxysilane.

[0019] The method for preparing a marine environment-stable superhydrophobic surface according to the present invention includes the following steps:

[0020] (1) Preparation of coating modifier (fluorosilicone modifier)

[0021] A fluorinated silane coupling agent was added to an organic solvent and ultrasonically dispersed for 5 minutes to obtain a coating modifier.

[0022] (2) Preparation of fluorosilane-modified silica

[0023] First, under stirring conditions, micron-sized silica particles and nano-sized silica particles are added to ethanol to form a dispersion with a mass percentage of 5%.

[0024] Then, a fluorosilane coupling agent and distilled water are added to the dispersion to form a mixture;

[0025] Finally, the mixture was placed in a nitrogen atmosphere at 70-100℃ for 2-4 hours, filtered, washed with ethanol 3-6 times to obtain a filter cake, dried, and obtained micro-nano fluorosilane modified silica.

[0026] The mass percentages of the fluorinated silane coupling agent and distilled water in the dispersion are both 1-5%.

[0027] (3) Preparation of epoxy resin mixture

[0028] Xylene is added to the epoxy resin to dissolve the epoxy resin, and the mixture is stirred evenly. Fluorosilane-modified silica is then evenly dispersed into the dissolved epoxy resin to obtain an epoxy resin mixture.

[0029] Dispersion is carried out using a disperser, with grinding beads used for auxiliary grinding and dispersion. The disperser speed is 300-1000 r / min, and the dispersion time is 0.5-1 h.

[0030] (4) Preparation of superhydrophobic surfaces

[0031] First, mix the epoxy resin mixture with the curing agent, stir well, brush it onto the substrate plate, and cure it at room temperature to form a coating.

[0032] Then, while the coating is in a semi-cured state, immerse the substrate plate in the coating modifier, or spray the coating modifier onto the surface of the semi-cured coating, let it stand for 0.5-2 hours, and then clean it with a solvent suitable for fluorinated silane coupling agents.

[0033] Finally, the substrate plate is dried at room temperature to 60°C until the coating is completely cured, resulting in a superhydrophobic surface.

[0034] Compared with existing technologies, this invention provides a superhydrophobic surface suitable for marine vehicles and its preparation method. The superhydrophobic surface uses epoxy resin as the film-forming material, and adds hydrophobically modified micron-sized silica and nano-sized silica to form a rough structure. During the semi-curing stage of the coating, it is treated with a coating modifier containing fluorinated silane. At this time, although the coating surface does not have fluidity, it has active hydroxyl groups. The hydroxyl groups react chemically with the fluorinated silane to graft the fluorinated silane onto the coating surface, effectively reducing the surface energy of the coating. Thus, the coating is endowed with superhydrophobicity from the aspects of rough structure and low surface energy material. Its preparation is simple, it has wide applicability, exhibits stable superhydrophobic properties in seawater, and retains its superhydrophobicity after being immersed in seawater, making it particularly suitable for marine vehicles. Attached image description:

[0035] Figure 1 This is a schematic diagram of a marine environment-stable superhydrophobic surface involved in Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of the static contact angle of a superhydrophobic surface that is stable in a marine environment, as described in Embodiment 2 of the present invention.

[0037] Figure 3This is a schematic diagram of the static contact angle of a superhydrophobic surface that is stable in a marine environment, as described in Embodiment 3 of the present invention. Specific implementation methods:

[0038] The present invention will be further described below with reference to the accompanying drawings and specific implementation methods.

[0039] Example 1:

[0040] The specific process of the method for preparing marine environment-stable superhydrophobic surfaces involved in this embodiment is as follows:

[0041] (1) Preparation of coating modifier

[0042] Add a fluorosilane coupling agent to a sealable container containing an organic solvent, and ultrasonically disperse for 5 minutes to obtain a coating modifier, wherein the volume fraction of the organic solvent is 1-10% and the volume fraction of the fluorosilane coupling agent is 90-99%.

[0043] (2) Preparation of fluorosilane-modified silica

[0044] First, under stirring conditions, 3.82g of micron-sized silica particles and 0.68g of nano-sized silica particles were added to 85.5g of ethanol to form a dispersion with a mass percentage of 5%.

[0045] Then, 3g of 1H,1H,2H,2H-perfluorooctyltrichlorosilane and 3g of distilled water were added to the dispersion to form a mixture;

[0046] Finally, the mixture was placed in a nitrogen atmosphere at 100°C and reacted for 2 hours. After filtration, the mixture was washed three times with ethanol to obtain a filter cake, which was then dried and ground to obtain micro-nano fluorosilane-modified silica.

[0047] (3) Preparation of epoxy resin mixture

[0048] Add 2g xylene to 3g E51 epoxy resin to dissolve the E51 epoxy resin, stir evenly, and use a disperser with a speed of 600r / min to evenly disperse 4g fluorosilane modified silica into the dissolved E51 epoxy resin to obtain epoxy resin mixture.

[0049] (4) Preparation of superhydrophobic surfaces

[0050] First, mix the epoxy resin mixture with the curing agent, stir well, brush it onto the substrate, and cure at room temperature.

[0051] Then, while the coating is in a semi-cured state, the substrate plate is immersed in the coating modifier for 1 hour and then cleaned with ethanol.

[0052] Finally, the substrate plate is dried at room temperature until the coating is completely cured, resulting in the following: Figure 1 The superhydrophobic surface shown.

[0053] Example 2:

[0054] This embodiment relates to the contact angle test of superhydrophobic surfaces stable in marine environments:

[0055] The superhydrophobic surface prepared in Example 1 was placed on a surface contact angle measuring instrument, and 5 μl of ultrapure water was added to the superhydrophobic surface. Figure 2 As shown, the measured static contact angle of the superhydrophobic surface is 165°, and the roll-off angle is 5°.

[0056] Example 3:

[0057] This embodiment involves stability testing of superhydrophobic surfaces in marine environments:

[0058] The superhydrophobic surface prepared in Example 1 was immersed in seawater for 24 hours and then removed. After the superhydrophobic surface dried, it was tested using the method described in Example 2. Figure 3 As shown, the static contact angle of the superhydrophobic surface after being soaked in seawater is 164°, the roll-off angle is 5°, and the superhydrophobic surface is intact, without bubbles, peeling, or detachment.

Claims

1. A method for preparing a marine-environment-stable superhydrophobic surface, wherein the superhydrophobic surface is formed by a coating and a coating modifier; characterized in that, The coating is made from an epoxy resin mixture and a curing agent, and the coating modifier consists of an organic solvent and a fluorinated silane coupling agent. The method for preparing a marine-environment-stable superhydrophobic surface includes the following steps: (1) Preparation of coating modifier A fluorinated silane coupling agent was added to an organic solvent and ultrasonically dispersed for 5 minutes to obtain a coating modifier. (2) Preparation of fluorosilane-modified silica First, under stirring conditions, micron-sized silica particles and nano-sized silica particles are added to ethanol to form a dispersion with a mass percentage of 5%. Then, a fluorosilane coupling agent and distilled water are added to the dispersion to form a mixture; Finally, the mixture was placed under a nitrogen atmosphere at 70-100℃ for 2-4 hours, filtered, washed with ethanol to obtain a filter cake, dried, and then fluorosilane-modified silica was obtained. The mass percentages of the fluorinated silane coupling agent and distilled water in the dispersion are both 1-5%. (3) Preparation of epoxy resin mixture Xylene is added to the epoxy resin to dissolve the epoxy resin and stirred evenly. Fluorosilane-modified silica is then evenly dispersed into the dissolved epoxy resin to obtain an epoxy resin mixture. The components and proportions of the epoxy resin mixture by mass percentage are: epoxy resin 30-50%, fluorosilane-modified silica 40-60%, and xylene 5-30%. (4) Preparation of superhydrophobic surfaces First, mix the epoxy resin mixture with the curing agent, stir well, brush it onto the substrate plate, and cure it at room temperature to form a coating. Then, while the coating is in a semi-cured state, immerse the substrate plate in the coating modifier, or spray the coating modifier onto the surface of the semi-cured coating, let it stand for 0.5-2 hours, and then clean it with ethanol. Finally, the substrate plate is dried at room temperature to 60°C until the coating is completely cured, resulting in a superhydrophobic surface.

2. The method for preparing a marine environment-stable superhydrophobic surface according to claim 1, characterized in that, The raw materials and proportions of the coating by mass percentage are: epoxy resin mixture 75-80%, curing agent 20-25%, and the components and proportions of the coating modifier by volume percentage are: fluorinated silane coupling agent 90-99%, organic solvent 1-10%.

3. The method for preparing a marine environment-stable superhydrophobic surface according to claim 1, characterized in that, The epoxy resin is E51 epoxy resin; in the silica used for fluorosilane-modified silica, the mass percentage of micron-sized silica is 40-90%, and the mass percentage of nano-sized silica is 10-60%.

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