阅读说明：本技术 一种水基自修复超疏水涂层及其制备方法 (Water-based self-repairing super-hydrophobic coating and preparation method thereof ) 是由 刘战剑 张聪源 苏言壮 汪怀远 王池嘉 李卡卡 于 2020-08-18 设计创作，主要内容包括：本发明涉及一种水基自修复超疏水涂层。解决了现有超疏水表面疏水耐久性差及仿生超疏水涂层中修复剂的稳定性差容易对环境造成污染的问题。其组分及配比按重量份数如下：水性聚合物乳液40-60份,纳微多尺度纤维5-10份,预聚物单体10-20份,造孔剂1-5份,纳米粒子1-10份,乳化剂1-5份,低表面能油类2-5份；蒸馏水20-50份。其制备方法包括：1)制备有机无机杂化乳化剂；2)制备有机无机杂化微胶囊；3)涂层制备过程：将多尺度纳米纤维粒子、造孔剂、水性聚合物乳液和制备的微胶囊分散在蒸馏水中,搅拌均匀后涂敷在金属或玻璃基板表面,干燥后,加热后制备本发明涂层。该水基自修复超疏水涂层,表面疏水耐久性好,具有高机械强度和自修复性能,有利于环保。(The invention relates to a water-based self-repairing super-hydrophobic coating. Solves the problems that the existing super-hydrophobic surface has poor hydrophobic durability and the repairing agent in the bionic super-hydrophobic coating has poor stability and easily causes environmental pollution. The components and the proportion are as follows according to parts by weight: 40-60 parts of water-based polymer emulsion, 5-10 parts of nano-micro multi-scale fibers, 10-20 parts of prepolymer monomers, 1-5 parts of pore-forming agent, 1-10 parts of nano particles, 1-5 parts of emulsifier and 2-5 parts of low-surface-energy oil; 20-50 parts of distilled water. The preparation method comprises the following steps: 1) preparing an organic-inorganic hybrid emulsifier; 2) preparing organic-inorganic hybrid microcapsules; 3) the preparation process of the coating comprises the following steps: the coating is prepared by dispersing the multi-scale nano-fiber particles, the pore-forming agent, the water-based polymer emulsion and the prepared microcapsules in distilled water, uniformly stirring, coating on the surface of a metal or glass substrate, drying and heating. The water-based self-repairing super-hydrophobic coating has good surface hydrophobic durability, high mechanical strength and self-repairing performance, and is beneficial to environmental protection.)

1. A water-based self-repairing super-hydrophobic coating is characterized in that: the components and the proportion are as follows according to parts by weight: 40-60 parts of water-based polymer emulsion, 5-10 parts of nano-micro multi-scale fibers, 10-20 parts of prepolymer monomers, 1-5 parts of pore-forming agent, 1-10 parts of nano particles, 1-5 parts of emulsifier and 2-5 parts of low-surface-energy oil; 20-50 parts of distilled water.

2. The water-based self-healing superhydrophobic coating of claim 1, wherein: the water-based polymer emulsion is one or a mixture of more of water-based epoxy resin, water-based ceramic emulsion, water-based organic silicon resin, water-based fluorocarbon resin and water-based polytetrafluoroethylene emulsion; the nano-micro multi-scale fiber is one or a mixture of carbon nano-fiber, carbon nano-tube, potassium titanate whisker and titanium oxide whisker.

3. The water-based self-healing superhydrophobic coating of claim 1, wherein: the prepolymer monomer is one or a mixture of formaldehyde solution, urea, resorcinol, isocyanate and polyether polyol; the low surface energy oil is one or a mixture of dimethyl silicone oil, amino silicone oil, hydroxyl silicone oil and hydroxyl fluorosilicone oil.

4. The water-based self-healing superhydrophobic coating of claim 1, wherein: the nano particles are one of nano silicon dioxide, nano titanium dioxide and nano anion powder.

5. The water-based self-healing superhydrophobic coating of claim 1, wherein: the emulsifier mainly comprises one or a mixture of more of octoxynol, gamma-isocyanic acid propyl triethoxysilane, gum arabic, polyvinyl alcohol and sodium dodecyl benzene sulfonate.

6. The water-based self-healing superhydrophobic coating of claim 1, wherein: the pore-forming agent is one of ammonium bicarbonate, ammonium chloride, sodium bicarbonate and ammonium nitrate.

7. The preparation method of the water-based self-repairing super-hydrophobic coating according to claim 1, characterized in that: the method comprises the following steps:

(1) the preparation process of the organic-inorganic hybrid emulsifier comprises the following steps:

weighing a certain amount of organic emulsifier and distilled water according to a proportion, uniformly mixing, then adding nanoparticles, carrying out ultrasonic oscillation, after uniform mixing, adjusting the pH to 7-9, heating in a water bath at 70 ℃ for 24h under a certain rotating speed condition, so that the organic emulsifier is grafted or adsorbed on the surfaces of the inorganic nanoparticles, and filtering and drying to obtain an organic-inorganic hybrid emulsifier;

(2) the preparation process of the organic-inorganic hybrid microcapsule comprises the following steps:

weighing a certain amount of low surface energy oil and a synthetic organic-inorganic hybrid emulsifier in proportion, adding the low surface energy oil and the synthetic organic-inorganic hybrid emulsifier into distilled water, and emulsifying by using an emulsifying machine at a certain rotating speed to prepare uniform O/W emulsion as a capsule core material; mixing the prepared O/W emulsion with a wall material prepolymer monomer solution, adjusting the pH of the mixed solution to 3-4, and stirring under the water bath heating condition of a certain rotating speed and 60-70 ℃; filtering and drying the reacted emulsion to obtain microcapsule powder;

(3) the preparation process of the coating comprises the following steps:

the method comprises the steps of dispersing multi-scale nano-fiber particles, a pore-forming agent, aqueous polymer emulsion and prepared microcapsules in distilled water according to a proportion, uniformly stirring by magnetic force for 2 hours, coating on the surface of a metal or glass substrate, drying at the temperature of-20-50 ℃, heating at the temperature of 150-220 ℃ after the aqueous solution is completely volatilized, and preparing the durable super-hydrophobic coating with self-repairing performance.

8. The preparation method of the water-based self-repairing super-hydrophobic coating as claimed in claim 7, wherein: the rotating speed of the step 1 is 300-400 r/min.

9. The preparation method of the water-based self-repairing super-hydrophobic coating as claimed in claim 7, wherein: the rotating speed of the emulsifying machine in the step 2 is 4000-; the stirring speed is 200-500r/min under the heating condition of the water bath.

10. The preparation method of the water-based self-repairing super-hydrophobic coating as claimed in claim 7, wherein: and the emulsifying time of the emulsifying machine in the step 2 is 25-40 min.

Technical Field

The invention relates to the technical field of hydrophobic materials, in particular to a water-based self-repairing super-hydrophobic coating and a preparation method thereof.

Background

The super-hydrophobicity of the solid surface refers to a state when the contact angle of a water drop and the surface is more than 150 degrees and the rolling angle is less than 10 degrees. In recent years, inspired by the super-hydrophobic property of animal and plant surfaces in nature, the bionic super-hydrophobic surface attracts wide attention of researchers due to good self-cleaning, antifouling, anti-adhesion, anti-corrosion and other properties. Through research on the super-hydrophobic surface in nature, the surface nano-micro structure and the low surface energy material are two necessary conditions for realizing the super-hydrophobic characteristics of the surfaces of animals and plants. Therefore, people can prepare the artificial super-hydrophobic surface by directly constructing the nano-micro multilevel structure on the surface of the low-surface-energy material or modifying the surface of the constructed nano-micro rough structure with the low-surface-energy material.

However, in practical application, the surface of the super-hydrophobic coating is inevitably affected by frictional wear or corrosion of acid and alkali media, so that the nano-micro structure or low surface energy substances on the surface of the coating are damaged, the super-hydrophobic characteristic of the surface is lost, and the large-scale application of the super-hydrophobic surface under practical conditions is severely limited. Because the hydrophobic stability of the coating surface is closely related to the stability of the surface nano-micro structure and the low surface energy material, the key to solve the problem of poor hydrophobic durability of the super-hydrophobic surface in practical application lies in how to enhance the mechanical strength of the nano-micro structure and improve the chemical stability of the low surface energy material of the coating surface.

In recent years, researchers prepare various durable bionic super-hydrophobic coatings through technical means such as chemical etching, electrodeposition, sol-gel, spraying and the like. For example, chinese patent (201910154580.2) discloses a method of combining acid-base etching with low surface energy modification to prepare a high temperature resistant super-hydrophobic coating on the surface of a steel pipe; chinese patent (201811103968.1) discloses that a multifunctional fluorine-containing furan is used as a low surface energy material to enhance the adhesive strength of a super-hydrophobic coating and the chemical stability of the surface; and an in-bin et al prepared a durable superhydrophobic coating having high mechanical strength and long-term Corrosion resistance by constructing a porous structure on a metal surface using oxalic acid anodizing and then combining a fluorosilane self-assembly method (corosion Science, 2019, 158: 108083.). Although the hydrophobic durability of the surface of the bionic super-hydrophobic coating can be effectively enhanced to a certain extent by constructing a nano-micro structure with high mechanical strength or improving the chemical stability of a low-surface-energy substance, the microstructure or the low-surface-energy material of the surface of the super-hydrophobic coating is still easily damaged under the conditions of strong acid, strong alkali or high abrasion, and the surface of the coating loses the super-hydrophobic property.

The research on the long-acting super-hydrophobic phenomenon of the plant surface in the nature discovers that when a low surface energy wax layer or a nano-micro structure on the plant surface is damaged, the surface loses the super-hydrophobic property, and the plant can restore the super-hydrophobic property of the surface through the nano-micro structure or the wax layer on the surface of a regeneration blade. Inspired by the self-repairing performance of plant surfaces in nature, people prepare various super-hydrophobic surfaces with self-repairing function by two ways of realizing the regeneration of nano-micro structures on the surface of a coating or pre-storing low surface energy materials in the coating. For example, Huangxin et al utilize the deformation mechanism of collagen fibers to regenerate the rough structure of the coated surface during sanding, thereby extending the superhydrophobic lifetime of the coated surface (Chemical Engineering Journal, 2018, 336: 633-. The Chinese patent (201910218015.8) utilizes the microcapsule containing fluorosilane to add into the coating to prepare the super-hydrophobic coating with self-repairing performance, when the coating surface is damaged, the fluorosilane can migrate to the coating surface to repair the damaged low surface energy substance on the coating surface. The inventor successfully prepares the self-repairing super-hydrophobic coating by constructing a three-dimensional porous structure on the surface of graphene through interface modification and a sol-gel method in an issued patent (201510507189.8) and storing a low-surface-energy material in a nanopore. However, due to the storage of low surface energy materials in the self-healing coating, there is a significant amount of pore structure in the coating, resulting in a decrease in the hardness and mechanical properties of the coating. Meanwhile, the low surface energy substances contained in the porous particle adsorption or polymer capsule have low stability, and the repairing agent leaks due to factors such as dissolution of an organic solvent or mechanical stirring in the coating emulsion preparation process, so that the self-repairing performance of the coating is seriously influenced, and the environment is polluted. Therefore, how to improve the stability of the low-surface-energy repairing agent in the coating by using an environment-friendly and effective method becomes a key for prolonging the super-hydrophobic durability of the surface of the coating.

Disclosure of Invention

The invention provides a water-based self-repairing super-hydrophobic coating, aiming at solving the problems that the existing super-hydrophobic surface has poor hydrophobic durability and the low-surface-energy repairing agent in the bionic super-hydrophobic coating has poor stability and easily causes environmental pollution in the background technology. The water-based self-repairing super-hydrophobic coating has good surface hydrophobic durability, high mechanical strength and self-repairing performance, and is beneficial to environmental protection; the invention also provides a preparation method of the water-based self-repairing super-hydrophobic coating.

The invention can solve the problems by the following technical scheme: a water-based self-repairing super-hydrophobic coating comprises the following components in parts by weight: 40-60 parts of water-based polymer emulsion, 5-10 parts of nano-micro multi-scale fibers, 10-20 parts of prepolymer monomers, 1-5 parts of pore-forming agent, 1-10 parts of nano particles, 1-5 parts of emulsifier and 2-5 parts of low-surface-energy oil; 20-50 parts of distilled water.

The water-based polymer emulsion is one or a mixture of more of water-based epoxy resin, water-based ceramic emulsion, water-based organic silicon resin, water-based fluorocarbon resin and water-based polytetrafluoroethylene emulsion; the nano-micro multi-scale fiber is one or a mixture of carbon nano-fiber, carbon nano-tube, potassium titanate whisker and titanium oxide whisker; the prepolymer monomer is one or more of formaldehyde solution, urea, resorcinol, isocyanate and polyether polyol; the low surface energy oil is one or more of dimethyl silicone oil, amino silicone oil, hydroxyl silicone oil and hydroxyl fluorosilicone oil; the pore-forming agent is one of ammonium bicarbonate, ammonium chloride, sodium bicarbonate and ammonium nitrate; the inorganic nano particles are one of nano silicon dioxide, nano titanium dioxide and nano anion powder; the organic emulsifier mainly comprises one or more of octoxynol, gamma-isocyanic acid propyl triethoxysilane, gum arabic, polyvinyl alcohol and sodium dodecyl benzene sulfonate.

The invention also provides a preparation method of the water-based self-repairing super-hydrophobic coating, which comprises the following steps:

(1) the preparation process of the organic-inorganic hybrid emulsifier comprises the following steps:

weighing a certain amount of organic emulsifier and distilled water according to a proportion, uniformly mixing, then adding nanoparticles, carrying out ultrasonic oscillation, after uniform mixing, adjusting the pH to 7-9, heating in a water bath at 70 ℃ for 24h under a certain rotating speed condition, so that the organic emulsifier is grafted or adsorbed on the surfaces of the inorganic nanoparticles, and filtering and drying to obtain an organic-inorganic hybrid emulsifier;

(2) the preparation process of the organic-inorganic hybrid microcapsule comprises the following steps:

weighing a certain amount of low surface energy oil and a synthetic organic-inorganic hybrid emulsifier in proportion, adding the low surface energy oil and the synthetic organic-inorganic hybrid emulsifier into distilled water, and emulsifying by using an emulsifying machine at a certain rotating speed to prepare uniform O/W emulsion as a capsule core material; mixing the prepared O/W emulsion with a wall material prepolymer monomer solution, adjusting the pH of the mixed solution to 3-4, and stirring under the water bath heating condition of a certain rotating speed and 60-70 ℃; filtering and drying the reacted emulsion to obtain microcapsule powder;

(3) the preparation process of the coating comprises the following steps:

the method comprises the steps of dispersing multi-scale nano-fiber particles, a pore-forming agent, aqueous polymer emulsion and prepared microcapsules in distilled water according to a proportion, uniformly stirring by magnetic force for 2 hours, coating on the surface of a metal or glass substrate, drying at the temperature of-20-50 ℃, heating at the temperature of 150-220 ℃ after the aqueous solution is completely volatilized, and preparing the durable super-hydrophobic coating with self-repairing performance.

The rotating speed in the step 1 is 300-; the rotating speed of the emulsifying machine in the step 2 is 4000-; the stirring speed is 200 and 500r/min under the water bath heating condition; and the emulsifying time of the emulsifying machine in the step 2 is 25-40 min.

The water-based self-repairing super-hydrophobic coating has the following functions:

(1) by selecting organic and inorganic hybrid materials as microcapsule wall materials, the problems of poor mechanical strength and easiness in breakage of a traditional microcapsule wall film are solved, and meanwhile, a nano rough structure is constructed on the surface of a micron-sized capsule, so that the super-hydrophobic stability of the surface of a coating is improved;

(2) the surface of the capsule prepared by using the organic-inorganic hybrid emulsifier is doped with a part of hydrophilic inorganic nano material, so that the prepared microcapsule can be uniformly dispersed in an aqueous solution, and the leakage of the low surface energy repairing agent caused by the dissolution of an organic solvent or the swelling of a wall membrane can be prevented;

(3) adding a water-soluble pore-forming agent into the aqueous emulsion of the coating, spraying the aqueous emulsion of the coating on the surface of the substrate, drying the aqueous emulsion at low temperature, separating out nano crystals from the pore-forming agent in situ in the coating, and decomposing the pore-forming agent in the coating and constructing a uniform porous structure on the surface of the coating in the heating and curing process, thereby being beneficial to improving the mechanical stability of the nano-micro structure on the surface of the coating;

(4) under the actual friction or corrosion condition, the damaged microcapsules can regenerate the rough structure of the surface of the coating, and meanwhile, the low-surface-energy substances embedded in the microcapsules can migrate to the surface of the coating under the influence of factors such as external pressure, temperature and the like, so that the damaged surface of the coating is covered by the low-surface-energy substances again, and the super-hydrophobicity of the surface of the coating is repaired.

Compared with the background technology, the invention has the following beneficial effects:

the invention mainly uses water as solvent to prepare coating emulsion in the process of preparing the coating, thereby avoiding the environmental pollution caused by the volatilization of organic solvent and having good environmental protection property. Meanwhile, the prepared organic-inorganic hybrid wall material microcapsule can be uniformly dispersed in water, so that the leakage of the repairing agent caused by dissolving or swelling the wall material by an organic solvent is effectively reduced, and the stability of the microcapsule in a coating emulsion is improved.

According to the invention, a water-soluble pore-forming agent is added into the coating water emulsion, and after low-temperature drying, the pore-forming agent precipitates nano crystals in situ in the coating, and the pore-forming agent is decomposed in the heating and curing process, so that a uniform and stable porous structure is constructed in and on the coating, the surface of the coating shows good super-hydrophobicity, and the contact angle with water can reach more than 155 degrees.

According to the invention, the organic-inorganic hybrid emulsifier is used for emulsifying the low surface energy oil, and the inorganic nanoparticles and the organic wall material are uniformly mixed in the polymerization process of the capsule wall material, so that the mechanical strength of the capsule wall material is enhanced, and the aims of increasing the yield and stability of the microcapsule are fulfilled. When the coating is damaged by corrosion, abrasion and damage, the low-surface-energy substances coated in the capsules migrate to the surface of the coating, so that the surface of the coating can recover the super-hydrophobic state again, and therefore, the super-hydrophobic coating prepared by the method has good self-repairing performance.

Drawings

FIG. 1 is an electron micrograph of a microcapsule prepared in inventive example 1;

FIG. 2 is a graph showing the change in contact angle of the surface of the coating after the self-repair test in example 1 of the present invention.

The specific implementation mode is as follows:

the following examples are given to illustrate the present invention in further detail, but the following examples should not be construed as limiting the scope of the invention, and some insubstantial modifications and adaptations of the invention in light of the above disclosure are intended to be covered thereby.

Example 1:

the specific preparation process of the water-based self-repairing super-hydrophobic coating is as follows:

the coating consists of the following raw materials in percentage by weight: 20 parts of aqueous epoxy emulsion, 30 parts of aqueous polytetrafluoroethylene emulsion, 5 parts of carbon nano-fiber, 15 parts of formaldehyde solution, 4 parts of urea, 2 parts of resorcinol, 3 parts of ammonium bicarbonate, 10 parts of nano-silica particles, 5 parts of sodium dodecyl benzene sulfonate and 5 parts of dimethyl silicone oil; 50 parts of distilled water.

(1) Substrate pretreatment:

the surface of the aluminum substrate is polished along a single direction by 600-mesh sand paper, then the aluminum substrate is placed into ethanol solution for ultrasonic cleaning, dust, grease and the like on the surface of the aluminum substrate are removed, and the aluminum substrate is taken out and dried for later use.

(2) The preparation process of the organic-inorganic hybrid emulsifier comprises the following steps:

adding 5 parts of sodium dodecyl benzene sulfonate and 10 parts of distilled water into a three-necked bottle, uniformly mixing, then adding 10 parts of nano-silica particles into the three-necked bottle, ultrasonically oscillating, uniformly mixing, adjusting the pH value to about 8, heating in a 70 ℃ water bath for 24 hours at the rotating speed of 350r/min to graft or adsorb the organic emulsifier on the surface of the inorganic nanoparticles, and filtering and drying to obtain the organic-inorganic hybrid emulsifier.

(3) The preparation process of the organic-inorganic hybrid microcapsule comprises the following steps:

and (3) adding 5 parts of dimethyl silicone oil and the organic-inorganic hybrid emulsifier synthesized in the step (2) into 20 parts of distilled water, and emulsifying for 30 min by using an emulsifying machine at the rotating speed of 6000 r/min to prepare uniform O/W emulsion as a capsule core material. Respectively adding 15 parts of O/W emulsion and formaldehyde solution, 4 parts of urea and 2 parts of resorcinol into a three-neck flask, adjusting the pH value of the solution to about 3, and stirring for 3 hours under the water bath heating condition of 70 ℃ at the rotating speed of 300 r/min. And filtering and drying the reacted emulsion to obtain microcapsule powder.

(4) The preparation process of the coating comprises the following steps:

and (2) dispersing 20 parts of aqueous epoxy emulsion, 30 parts of aqueous polytetrafluoroethylene emulsion, 5 parts of carbon nanofiber, 3 parts of ammonium bicarbonate and the microcapsule prepared in the step (3) in 20 parts of distilled water, uniformly stirring by magnetic force for 2 hours, coating on the surface of an aluminum substrate, drying at 30 ℃, heating at 180 ℃ for 30 min after the aqueous solution is completely volatilized, and preparing the durable super-hydrophobic coating with self-repairing performance.

The properties of the coating were determined as follows:

a hydrophobicity: the contact angle between the surface of the coating and 10 mu L of water drops can reach 158 degrees and the rolling angle is 7 degrees by adopting a static contact angle measuring instrument.

b, wear resistance: the 600-mesh sand paper is used for performing a friction experiment on the prepared super-hydrophobic coating under the load condition of 200 g, and after 1000 times of friction experiments, the surface hydrophobic angle of the coating can still be kept above 150 degrees, which shows that the prepared super-hydrophobic coating has excellent wear resistance and hydrophobic stability.

c chemical stability: the coating is soaked in a strong acid-base solution with pH =1 and 14 or the coating is irradiated under a 30W ultraviolet lamp, and after 14 days, the hydrophobic angle of the surface of the coating can still be kept above 150 degrees, which indicates that the coating has good chemical stability.

d self-repairing performance: the prepared super-hydrophobic coating was polished under 500 g load with 400 mesh sandpaper, and the surface hydrophobic angle of the coating was reduced to 141 ° after 500 rubs. The coating is kept stand for 24 hours at room temperature or heated for 20 minutes at 80 ℃, and the hydrophobic angle of the surface of the coating is recovered to about 158 degrees, which shows that the coating has good self-repairing performance.