Super-hydrophobic coating with honeycomb microporous structure and preparation method of super-hydrophobic coating

Abstract

According to the super-hydrophobic coating with the honeycomb microporous structure and the preparation method of the super-hydrophobic coating, the preparation process is simple, convenient and controllable, a complex template is not needed, and convenience and stability are taken into account through two-stage stepped heating curing and coordinated regulation and control of volatilization of a pore-forming agent, migration and enrichment of fluorinated nano SiO2 and crosslinking of resin. Honeycomb micropores are formed in situ by a pore-forming agent to construct a macroscopic rough skeleton, and fluorinated nano SiO2 is enriched on pore walls and surfaces to form a micro-nano hierarchical structure; the elastic core of the core-shell particle absorbs impact, disperses crazes, and cooperates with a resin cross-linked network to improve the toughness, impact resistance and strength of the coating. In the aspect of super-hydrophobicity, fluorinated nano SiO2 provides low surface energy and nano roughness as a basis, subsequent fluorosilane deposition is grafted with a perfluorinated chain to optimize surface energy, excellent and lasting super-hydrophobicity is endowed, unification of process, mechanical property, super-hydrophobicity and durability is finally realized, and application requirements are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional coating materials, in particular to a super-hydrophobic coating with a honeycomb-like microporous structure and a preparation method thereof. BACKGROUND

[0002] Super-hydrophobic coatings (water contact angle > 150°, rolling angle < 10°) have broad application prospects in the fields of ice prevention, corrosion prevention, oil stain prevention, and liquid adhesion prevention. From the performance requirements, to achieve super-hydrophobicity, the coating surface needs to meet the core conditions of water contact angle > 150° and rolling angle < 10°, and the core feature is the synergistic existence of high water contact angle and low rolling angle.

[0003] From the technical principle, the key to constructing a super-hydrophobic surface currently lies in possessing two major elements: one is to form a micro-nano hierarchical rough structure, and the other is to introduce a low surface energy material, both of which work together to achieve super-hydrophobicity. In terms of porous structure construction, the commonly used preparation methods in the prior art include template method (such as using salt particles, polymer microspheres, etc. as templates), phase separation method, electrospinning method, etc. However, such methods generally have obvious limitations: the process operation is complicated, the template is difficult to completely remove, the equipment precision requirement is high, and the finally prepared coating also has problems such as low mechanical strength and easy damage, which is difficult to meet the actual application requirements.

[0004] Therefore, it is of important practical significance to develop a coating with simple process, high structural stability, excellent toughness, and durable super-hydrophobicity, which can promote the practical application of super-hydrophobic technology in various fields. SUMMARY

[0005] The present application aims to provide a super-hydrophobic coating with a honeycomb-like microporous structure and a preparation method thereof, to overcome the deficiencies in the prior art. Specifically, the commonly used methods for constructing porous structures in the prior art include template method (such as using salt particles, polymer microspheres, etc. as templates), phase separation method, electrospinning method, etc. However, these methods often have problems such as complex process, difficult template removal, high equipment requirement, and poor mechanical properties of the coating. The present technical solution has the characteristics of simple process and no need for complex post-processing. The coating prepared by the present solution not only has a significant micro-nano structure, but also has excellent hydrophobicity and toughness.

[0006] To achieve the above-mentioned purpose, the present application first provides a preparation method of a super-hydrophobic coating with a honeycomb-like microporous structure, comprising: S10, mixing core-shell polymer particles and water-based epoxy resin and then performing shearing treatment to obtain a suspension; S20, mixing the suspension with a volatile organic pore-forming agent, uniformly dispersing by stirring to obtain an emulsion; S30, mixing the emulsion, fluorinated nano-SiO2 particles and dispersant, and then performing shearing treatment to obtain a suspension slurry; S40, mixing the suspension slurry and the epoxy resin curing agent in a proper proportion, and then stirring uniformly to obtain a composite slurry; S50, spraying the composite slurry on the surface of the pretreated substrate, and performing two-stage temperature rising curing to volatilize the volatile organic pore-forming agent and promote the crosslinking of the resin, thereby forming a honeycomb micro-porous structure coating; S60, performing fluorosilane vapor deposition treatment on the honeycomb micro-porous structure coating to obtain a super-hydrophobic coating with a honeycomb micro-porous structure.

[0007] Preferably, in the step S10, the core-shell polymer particles have a core-shell structure, the core is an acrylate copolymer elastomer, and the shell is one of polymethyl methacrylate or an acrylate polymer containing an epoxy functional group, and the average particle size of the core-shell polymer particles is 100-500 nm.

[0008] Preferably, in the step S10, the mass ratio of the core-shell polymer particles to the water-based epoxy resin is 1:(10-20).

[0009] Preferably, in the step S20, the volatile organic pore-forming agent includes an organic solvent with a boiling point of 50-120°C, and the organic solvent includes at least one of butyl acetate, acetone and ethyl acetate; the mass ratio of the suspension to the volatile organic pore-forming agent is (5-20):1.

[0010] Preferably, in the step S30, the fluorinated nano-SiO2 particles are hydrophobic fumed silica surface-modified by heptadecafluorodecyltriethoxysilane, the average particle size is 7-40 nm, the specific surface area is 150-300 m 2 / g, and the addition amount is 3-6% of the mass of the water-based epoxy resin; the dispersant is a high-molecular-weight super-dispersant of BYK-154 type, and the addition amount is 20-60% of the mass of the fluorinated nano-SiO2 particles.

[0011] Preferably, in the step S40, the molar ratio of the active hydrogen in the epoxy resin curing agent to the epoxy groups in the water-based epoxy resin is (0.8-1.2):1.

[0012] Preferably, in the step S50, the substrate includes at least one of concrete and bridge ropes, and the step of pretreating the substrate includes polishing, cleaning and drying in sequence.

[0013] Preferably, the step S50 specifically includes: S501, placing the pretreated substrate sprayed with the composite slurry in an oven, and heating at 60-80°C for 20-60 min; S502, the oven temperature is raised to 115~125℃, and heated and cured for 1~3h to obtain a honeycomb microporous structure coating.

[0014] Preferably, the step S60 specifically comprises: The honeycomb microporous structure coating is subjected to vapor deposition treatment of perfluorodecyltriethoxysilane; wherein the amount of perfluorodecyltriethoxysilane is 50~200μL based on 1~2L of a closed container, the purity is ≥95%, the deposition temperature is controlled to be 90~100℃, and the deposition time is 2~4h.

[0015] Correspondingly, the application also provides a honeycomb microporous structure super-hydrophobic coating prepared by the method for preparing the honeycomb microporous structure super-hydrophobic coating according to any one of the above.

[0016] The beneficial effects of the present application are: different from the prior art, the present application provides a super-hydrophobic coating with a honeycomb microporous structure and a preparation method thereof, the preparation method comprises the following steps: firstly, core-shell polymer particles are mixed with water-based epoxy resin and then subjected to shearing treatment to obtain a suspension; secondly, the suspension is mixed with a volatile organic pore-forming agent, and after uniform stirring and dispersion, an emulsion is obtained; thirdly, the emulsion, fluorinated nano-SiO2 particles and a dispersing agent are mixed and then subjected to shearing treatment to obtain a suspension slurry; fourthly, the suspension slurry is mixed with an epoxy resin curing agent in a proper proportion and then stirred uniformly to obtain a composite slurry; fifthly, the composite slurry is sprayed on the surface of a pretreated substrate, and through two-stage stepwise temperature curing, the volatile organic pore-forming agent is volatilized and the resin is crosslinked to form a honeycomb microporous structure coating; finally, the honeycomb microporous structure coating is subjected to fluorosilane vapor deposition treatment to obtain a super-hydrophobic coating with a honeycomb microporous structure. The preparation method provided by the present application has the advantages of simple and controllable process, without the need for a complex template removal step, and through two-stage stepwise temperature curing, the slow and complete volatilization of the pore-forming agent, the ordered migration and enrichment of the fluorinated nano-SiO2, and the full crosslinking of the resin are synergistically controlled, which not only ensures the convenience of operation but also ensures the stability of the process; on this basis, on the one hand, the volatile pore-forming agent is used to form a regular honeycomb microporous structure to construct a macroscopic roughness skeleton, and the fluorinated nano-SiO2 is enriched on the pore wall and the surface under the driving of interfacial energy to form a stable micro-nano hierarchical structure, which lays a structural foundation for performance, and on the other hand, the elastomer core of the core-shell polymer particle absorbs impact energy and disperses silver lines, and the three-dimensional network formed by the full crosslinking of the resin significantly improves the toughness, impact resistance and mechanical strength of the coating; in terms of super-hydrophobic performance, the fluorinated nano-SiO2 itself provides a basis for hydrophobicity with low surface energy and nano-scale roughness, and the subsequent fluorosilane vapor deposition further optimizes the surface energy by grafting dense and well-oriented perfluoroalkyl long chains, so that the coating has excellent super-hydrophobicity and durability, and finally realizes the balance and unity of the coating process, mechanical properties, super-hydrophobicity and durability, which can meet the actual application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The preparation method flow chart of the super-hydrophobic coating with a honeycomb microporous structure provided by the embodiments of the present application; Figure 2 The water contact angle test photo of the super-hydrophobic coating with a honeycomb microporous structure provided by embodiment 1. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0019] In view of the defects of the prior art, the present inventors have found, through long-term research and a large number of practices, that epoxy resin is widely used as a coating matrix due to its excellent adhesion, mechanical properties and chemical stability, but it is itself hydrophilic. It is often difficult to form a stable micro-nano hierarchical structure by simply blending hydrophobic nanoparticles into the epoxy resin. Therefore, the present inventors have proposed the technical solutions of the present application according to the characteristics of the hydrophilic nature of the epoxy resin itself and the difficulty of the hydrophobic nanoparticles to form a stable micro-nano hierarchical structure. The technical solutions of the present application will be clearly and completely described below, which mainly relates to a super-hydrophobic coating with a honeycomb-like microporous structure and a preparation method thereof. The super-hydrophobic coating is based on the synergistic effect of the two aspects of "fluorinated nano-SiO2 particles enriched on the surface of the coating" and "construction of a honeycomb-like microstructure", which endows the coating with excellent and stable super-hydrophobic properties.

[0020] Please refer to Figure 1 , Figure 1 The preparation method flow chart of the super-hydrophobic coating with a honeycomb-like microporous structure provided in the embodiments of the present application; wherein the above preparation method specifically comprises: S10, mixing the core-shell polymer particles with the water-based epoxy resin and then performing shearing treatment to obtain a suspension.

[0021] Specifically, the S10 step further comprises: The core-shell polymer particles are added to the water-based epoxy resin (component A) and subjected to high-speed shearing treatment to form a stable suspension; wherein the water-based epoxy resin can be selected from at least one of bisphenol A type emulsified water-based epoxy resin, carboxyl modified self-emulsified water-based epoxy resin, epoxy acrylate modified water-based epoxy resin and silicone modified water-based epoxy resin.

[0022] Specifically, the S10 step can not only break the particle agglomeration by shearing force to achieve uniform dispersion of the core-shell polymer particles in the resin system and avoid local defects in the coating caused by uneven dispersion, but also prevent particle sedimentation by virtue of the stable suspension state to ensure the uniformity of the system in subsequent process steps.

[0023] In the S10 step, the core-shell polymer particles have a core-shell structure, the core is an acrylate copolymer elastomer, and the shell is one of polymethyl methacrylate or an acrylate polymer containing an epoxy functional group, and the average particle size of the core-shell polymer particles is 100-500 nm.

[0024] Specifically, the core-shell polymer particles can not only absorb impact energy through the elastomer core, disperse silver cracks, significantly improve the toughness and impact resistance of the coating, but also realize uniform dispersion by the good compatibility of the shell material with the waterborne epoxy resin. The shell layer containing epoxy functional groups can also cross-link with the resin to enhance the bonding force, and its particle size can assist in subsequent construction of stable micro-nano rough structure, laying a foundation for optimizing the comprehensive performance of the coating.

[0025] In the S10 step, the mass ratio of the core-shell polymer particles to the waterborne epoxy resin is 1:(10-20); the above mass ratio can not only ensure uniform dispersion of the core-shell particles in the resin system, avoid agglomeration due to excessive amount, and affect the uniformity of the coating, but also ensure that the functions of "toughening by elastic core and promoting compatibility by shell" are fully exerted.

[0026] In the S10 step, the high-speed shearing treatment is to use an LM25-D high-speed dispersion shearing machine (digital display type) to disperse for 30-60 min at a speed of 1000-3000 rpm; the above high-speed shearing treatment can not only ensure rapid and uniform dispersion of the core-shell polymer particles in the waterborne epoxy resin system by the precise digital control and stable shearing force of the equipment, completely break the particle agglomerates, and avoid defects in the coating due to uneven dispersion; but also allow the particles and the resin to fully contact by adapting the speed and time, and strengthen the compatibility of the shell layer and the resin.

[0027] S20, mixing the suspension and the volatile organic pore-forming agent, and uniformly dispersing after stirring to obtain an emulsion.

[0028] Specifically, the S20 step further comprises: mixing the suspension and the volatile organic pore-forming agent, and high-speed stirring to form a uniform emulsion; the S20 step can not only realize uniform dispersion of the volatile organic pore-forming agent in the suspension system by the shearing force of high-speed stirring, avoid uneven size and chaotic distribution of the pores formed subsequently due to agglomeration of the volatile organic pore-forming agent, but also ensure the interfacial compatibility of the volatile organic pore-forming agent with the core-shell polymer particles and the waterborne epoxy resin by the stable emulsion state, laying a foundation for slow and complete volatilization of the volatile organic pore-forming agent and in-situ formation of regular honeycomb-like microporous structure in the subsequent curing stage.

[0029] In the S20 step, the volatile organic pore-forming agent includes an organic solvent with a boiling point of 50-120°C, and the organic solvent includes at least one of butyl acetate, acetone and ethyl acetate; the mass ratio of the suspension to the volatile organic pore-forming agent is (5-20):1.

[0030] Specifically, the volatile organic pore-forming agent can be slowly and completely volatilized at a low temperature stage of subsequent stepwise temperature curing by adapting the boiling point, avoiding premature escape or residue, and can be uniformly dispersed by the good compatibility of the selected solvent with the system; meanwhile, a reasonable mass ratio can ensure the formation of a suitable number of micron-sized pores uniformly distributed, which not only builds the macroscopic roughness skeleton required for superhydrophobicity, but also avoids loose coating structure caused by excessive pore-forming agents, and takes into account the integrity of micro-nano structure and the stability of mechanical properties.

[0031] S30, mixing the emulsion, fluorinated nano-SiO2 particles and dispersant, and then performing shearing treatment to obtain a suspension slurry.

[0032] Specifically, the S30 step further comprises: The fluorinated nano-SiO2 particles and the dispersant are added to the emulsion, and high-speed shearing treatment is performed to uniformly disperse them, forming a stable suspension slurry; wherein, the S30 step can not only break the agglomeration of fluorinated nano-SiO2 particles by the synergistic effect of dispersant and high-speed shearing, but also realize uniform dispersion in the system, and prevent particle sedimentation by stable slurry state to ensure system uniformity in subsequent processes; meanwhile, uniformly dispersed fluorinated nano-SiO2 can fully play the core role of providing nano-scale roughness and low surface energy, and together with the dispersant, it can strengthen the anchoring effect of particles in the resin network, laying a solid foundation for subsequent construction of stable micro-nano hierarchical structure and improvement of coating superhydrophobicity and mechanical stability.

[0033] In the S30 step, the fluorinated nano-SiO2 particles are hydrophobic fumed silica surface-modified by heptadecafluorodecyltriethoxysilane, with an average particle size of 7-40 nm and a specific surface area of 150-300 m 2 / g, and the addition amount is 3-6% of the mass of the waterborne epoxy resin; the dispersant is a high-molecular-weight superdispersant of BYK-154 type from BYK Company, and the addition amount is 20%-60% of the mass of the fluorinated nano-SiO2 particles.

[0034] Specifically, the fluorinated nano-SiO2 particles can break the agglomeration of particles by the adaptability of dispersant and SiO2, realize uniform dispersion in the system, and avoid defects in the coating structure caused by agglomeration; can construct nano-scale roughness by the small particle size and large specific surface area of SiO2, and lay a foundation for superhydrophobicity by the low surface energy imparted by surface modification; meanwhile, the appropriate addition amount can ensure good compatibility with the resin system, and firmly anchor in the resin network, which not only enhances the mechanical stability of the coating, but also cooperates with the macroscopic rough structure formed by subsequent pore-forming to construct a stable micro-nano hierarchical structure, realizing the synergistic optimization of superhydrophobicity and mechanical properties.

[0035] In the S30 step, the high-speed shearing treatment is performed using an LM25-D high-speed dispersion shearing machine (digital display type) at a rotation speed of 5000-15000 rpm for 10-30 min; wherein, through the synergistic effect of high shear force and dispersing agent, the agglomeration of fluorinated nano-SiO2 particles can be completely broken, realizing uniform and stable dispersion in the system, avoiding structural defects in the coating due to particle agglomeration; at the same time, the appropriate rotation speed and time can allow the particles to fully contact the emulsion components, strengthen the interface bonding with the resin, lay the foundation for subsequent efficient construction of nano-scale roughness, stable anchoring in the resin network, and further ensure the integrity of the micro-nano hierarchical structure of the coating and the synergistic optimization of super-hydrophobic and mechanical properties.

[0036] In S40, the suspension slurry is mixed with the epoxy resin curing agent (component B) in proportion and stirred uniformly to obtain a composite slurry.

[0037] Specifically, in the S40 step, the suspension slurry and the epoxy resin curing agent are fully stirred using an LM25-D high-speed dispersion shearing machine (digital display type) at a rotation speed of 1000-3000 rpm for 30-60 min to obtain a composite slurry.

[0038] In the S40 step, the epoxy resin curing agent can be selected from amine curing agents suitable for water-based epoxy resins, including fatty amine water-based curing agents, polyamide water-based curing agents, amine-cured epoxy adduct modified curing agents, etc. - The fatty amine has high reactivity, can be preliminarily crosslinked at a low temperature stage with ladder heating and completely cured at a high temperature stage, has good compatibility with the resin, and can enhance the coating density; polyamide has excellent toughness, can synergize with the toughening effect of core-shell particles, and further improve the impact resistance of the coating; amine-cured epoxy adduct has strong stability and controllable crosslinking speed, can react with the shell layer of core-shell particles containing epoxy functional groups, strengthen the bonding force between particles and resin network, and meet the overall process requirements.

[0039] In the S40 step, the amount of epoxy resin curing agent is determined according to the epoxy value of the epoxy resin, and the molar ratio of active hydrogen in the epoxy resin curing agent to the epoxy group in the water-based epoxy resin is (0.8-1.2):1; wherein, the amount of epoxy resin curing agent is designed to prevent insufficient active hydrogen from causing incomplete crosslinking, resulting in poor mechanical strength and density of the coating, and to avoid excessive active hydrogen causing curing agent residue, affecting the super-hydrophobic durability and chemical stability of the coating; at the same time, the precise amount and ratio can adapt to the two-stage ladder heating curing process, help the resin to preliminarily gel at the low temperature stage to fix the micro-nano structure, and completely crosslink at the high temperature stage to form a stable three-dimensional network, strengthen the interface bonding of core-shell polymer particles, fluorinated nano-SiO2 and resin, and finally ensure the balance of mechanical properties, structural stability and super-hydrophobic performance of the coating in batch production.

[0040] S50, spraying the composite slurry on the pretreated substrate surface, and forming a honeycomb microporous structure coating by two-stage temperature rising curing to volatilize the volatile organic pore-forming agent and promote the crosslinking of the resin.

[0041] Specifically, the process of forming a honeycomb microporous structure coating by two-stage temperature rising curing in the S50 step specifically includes: The first stage curing (volatile pore-forming and structure forming): the coated wet film is placed in an oven at 60-80℃ for heating for 20-60min. The volatile pore-forming agent in the system volatilizes under heating, leaving numerous micron-sized holes in the resin film to form a honeycomb structure skeleton. At the same time, the low-surface-energy hydrophobic fluorinated nano-SiO2 particles migrate and enrich on the pore wall and the coating surface under the driving of the interfacial energy. The second stage curing (complete crosslinking and structure fixing): the temperature is raised to 115-125℃ for heating and curing for 1-3h. The epoxy resin and the curing agent undergo complete crosslinking reaction to form a tough three-dimensional network structure, which firmly anchors the hydrophobic fluorinated nano-SiO2 particles that have been enriched on the surface, thereby permanently fixing the micro-nano hierarchical structure.

[0042] Specifically, the two-stage temperature rising process of the S50 step can not only make the volatile pore-forming agent volatilize fully and form a regular honeycomb microporous skeleton in situ in the first stage, and drive the ordered migration and enrichment of the fluorinated nano-SiO2 particles on the pore wall and the coating surface, laying a foundation for the construction of the micro-nano hierarchical structure and the superhydrophobic performance, but also can promote the complete crosslinking of the epoxy resin and the curing agent in the second stage by high temperature, form a tough three-dimensional network, firmly anchor the enriched fluorinated nano-SiO2 particles, permanently fix the micro-nano structure, and further improve the mechanical strength and structural stability of the coating by synergizing with the toughening effect of the core-shell polymer particles, finally realize the step-by-step coordination of micropore forming-particle enrichment-structure fixing, and guarantee the balance and unity of the integrity of the micro-nano structure, the superhydrophobic performance and the mechanical performance of the coating.

[0043] In the S50 step, the substrate includes at least one of concrete and bridge rope, and the pretreatment of the substrate includes polishing, cleaning and drying in sequence; wherein the above-mentioned substrate is selected to not only adapt to the actual application scene of the superhydrophobic coating, but also significantly improve the interfacial bonding force between the composite slurry and the substrate by polishing to increase the surface roughness of the substrate, cleaning to remove impurities and oil stains, and drying to eliminate water interference; at the same time, it provides a clean, dry and rough adhesion substrate for the subsequent formation of a honeycomb microporous structure and a micro-nano hierarchical structure in the coating curing, avoids the peeling, cracking or uneven performance of the coating due to improper pretreatment of the substrate, and guarantees the adhesion, structural stability, superhydrophobic durability and mechanical performance of the coating in the actual application scene, which adapts to the demand of outdoor harsh environment.

[0044] S60, the honeycomb microporous structure coating is subjected to fluorosilane vapor deposition treatment to obtain a super-hydrophobic coating with a honeycomb microporous structure.

[0045] Specifically, the S60 step specifically comprises: The honeycomb microporous structure coating is subjected to perfluorodecyltriethoxysilane vapor deposition treatment; wherein the amount of perfluorodecyltriethoxysilane is 50 μL to 200 μL based on a closed container of 1 to 2 L, the purity is ≥ 95%, the deposition temperature is controlled to be 90°C to 100°C, and the deposition time is 2 h to 4 h.

[0046] Specifically, the fluorosilane vapor deposition treatment of the honeycomb microporous structure coating can take advantage of the low surface energy characteristics of fluorosilane, cooperate with the existing micro-nano hierarchical structure of the coating, further strengthen the super-hydrophobic performance, and improve the surface hydrophobic stability and anti-pollution ability; meanwhile, the dense film formed by deposition can enhance the wear resistance and aging resistance of the coating, prolong the service life, and ultimately ensure the performance of the super-hydrophobic coating to be durable and stable in actual application scenarios, and adapt to the needs of outdoor harsh environments.

[0047] Correspondingly, the application also provides a super-hydrophobic coating with a honeycomb microporous structure, which is prepared by the preparation method of the super-hydrophobic coating with a honeycomb microporous structure according to any one of the above; wherein the conductivity of the super-hydrophobic coating increases by 1 order of magnitude in 28 days, and the electromagnetic shielding ability is improved by 252%.

[0048] The technical solutions of the application will be further described in detail below in combination with several preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the application, and do not have any limiting effect on the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the application. If the experimental methods are not specified in the following embodiments, the methods are usually performed under conventional conditions or under conditions recommended by the manufacturer.

[0049] Embodiment 1: Embodiment 1 provides a super-hydrophobic coating with a honeycomb microporous structure and a preparation method thereof, and the preparation method comprises the following steps: Step one, the core-shell polymer particles are added to the water-based epoxy resin (component A), and a stable suspension is formed by high-speed shearing treatment; wherein the mass ratio of the core-shell polymer particles to the epoxy resin (component A) is 1:15; the high-speed shearing treatment is to use an LM25-D high-speed dispersion shearing machine (digital display type) to disperse for 40 min at a rotation speed of 2000 rpm; Step two, mix the above suspension with volatile organic pore-forming agent to form a uniform emulsion by high-speed stirring; wherein the volatile organic pore-forming agent is butyl acetate, and the mass ratio of the suspension to the volatile organic pore-forming agent is 15:1; Step three, add fluorinated nano-SiO2 particles and dispersant to the emulsion, and uniformly disperse them by high-speed shearing treatment to form a stable suspension slurry; wherein the fluorinated nano-SiO2 particles are hydrophobic fumed SiO2 whose surface is modified by heptadecafluorodecyltriethoxysilane, the average particle size is 30 nm, the specific surface area (BET) is 200 m 2 / g, and the addition amount is 4wt% of the content of the epoxy resin (component A); the dispersant is BYK-154 type high molecular super dispersant of BYK company, and the addition amount is 40wt% of the fluorinated nano-SiO2 particles; the high-speed shearing treatment is to use LM25-D high-speed dispersion shearing machine (digital display type) to disperse for 20 min at a speed of 10000 rpm; Step four, add the epoxy resin curing agent (component B) to the suspension slurry, and fully stir until uniform to obtain a composite slurry; wherein the amount of the epoxy resin curing agent (component B) is determined according to the epoxy value of the epoxy resin, so that the molar ratio of active hydrogen to epoxy group in the curing agent (component B) is 1:1; the fully stirring until uniform is to use LM25-D high-speed dispersion shearing machine (digital display type) to disperse for 60 min at a speed of 3000 rpm; Step five, spray the super-hydrophobic coating slurry to the surface of the pretreated substrate, and form a honeycomb micro-porous structure coating by two-stage ladder temperature curing; wherein the substrate includes any one of concrete or bridge rope, and the pretreatment of the substrate includes grinding, cleaning, drying and the like; the two-stage ladder temperature curing includes: first, place the pretreated substrate sprayed with the composite slurry in an oven, heat at 70℃ for 40 min; second, increase the temperature of the oven to 120℃, and heat and cure for 2h to obtain a honeycomb micro-porous structure coating.

[0050] Step six, perform low-temperature fluorosilane vapor deposition treatment on the honeycomb micro-porous structure coating to finally obtain a super-hydrophobic coating with a honeycomb micro-porous structure, as shown in Figure 2 ; Figure 2 The water contact angle CA of the implementation example is 166.6°, which proves that it has super-hydrophobic properties); wherein the low-temperature fluorosilane vapor deposition treatment is to perform perfluorodecyltriethoxysilane vapor deposition treatment on the coating, the amount of fluorosilane is 150μL (volume 1~2L closed container), the purity is greater than 95%, the deposition temperature is 95℃, and the deposition time is 3h.

[0051] Example 2: Example 2 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 2 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 1, the mass ratio of the core-shell polymer particles to the aqueous epoxy resin (A component) is 1:10.

[0052] Example 3: Example 3 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 3 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 1, the mass ratio of the core-shell polymer particles to the aqueous epoxy resin (A component) is 1:20.

[0053] Example 4: Example 4 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 4 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 2, the mass ratio of the suspension containing the core-shell polymer particles to the volatile organic pore-forming agent is 5:1.

[0054] Example 5: Example 5 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 5 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 2, the mass ratio of the suspension containing the core-shell polymer particles to the volatile organic pore-forming agent is 20:1.

[0055] Example 6: Example 6 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 6 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 3, the amount of the fluorinated nano-SiO2 particles added is 3 wt% of the content of the aqueous epoxy resin (A component).

[0056] Example 7: Example 7 provides a superhydrophobic coating having a honeycomb-like microporous structure and a method for preparing the same. The method for preparing the superhydrophobic coating provided in Example 7 is substantially the same as the method for preparing the superhydrophobic coating provided in Example 1, except that in Step 3, the amount of the fluorinated nano-SiO2 particles added is 6 wt% of the content of the aqueous epoxy resin (A component).

[0057] Example 8: Example 8 provides a superhydrophobic coating with honeycomb-like microporous structure and a method for preparing the same. The method provided in Example 8 is substantially the same as the method provided in Example 1, except that the two-stage temperature ramping curing in Step V is as follows: first, the pretreated substrate sprayed with the composite slurry is placed in an oven and heated at 60°C for 20 min; second, the temperature of the oven is increased to 115°C and heated for 1 h to obtain the honeycomb-like microporous structure coating.

[0058] Example 9: Example 9 provides a superhydrophobic coating with honeycomb-like microporous structure and a method for preparing the same. The method provided in Example 9 is substantially the same as the method provided in Example 1, except that the two-stage temperature ramping curing in Step V is as follows: first, the pretreated substrate sprayed with the composite slurry is placed in an oven and heated at 80°C for 60 min; second, the temperature of the oven is increased to 125°C and heated for 3 h to obtain the honeycomb-like microporous structure coating.

[0059] Example 10: Example 10 provides a superhydrophobic coating with honeycomb-like microporous structure and a method for preparing the same. The method provided in Example 10 is substantially the same as the method provided in Example 1, except that the low-temperature fluorosilane vapor deposition treatment in Step VI is as follows: the low-temperature fluorosilane vapor deposition treatment is a vapor deposition treatment of perfluorodecyltriethoxysilane, the amount of fluorosilane used is 50 μL (volume of 1-2 L closed container), the purity is greater than 95%, the deposition temperature is 90°C, and the deposition time is 2 h.

[0060] Example 11: Example 11 provides a superhydrophobic coating with honeycomb-like microporous structure and a method for preparing the same. The method provided in Example 11 is substantially the same as the method provided in Example 1, except that the low-temperature fluorosilane vapor deposition treatment in Step VI is as follows: the low-temperature fluorosilane vapor deposition treatment is a vapor deposition treatment of perfluorodecyltriethoxysilane, the amount of fluorosilane used is 200 μL (volume of 1-2 L closed container), the purity is greater than 95%, the deposition temperature is 100°C, and the deposition time is 4 h.

[0061] Comparative Example 1: Comparative Example 1 provides a superhydrophobic coating with honeycomb-like microporous structure and a method for preparing the same. The method provided in Comparative Example 1 is substantially the same as the method provided in Example 1, except that no core-shell polymer particles are added in Step I.

[0062] Comparative Example 2: Comparative Example 2 provides a super-hydrophobic coating with honeycomb micro-porous structure and a method for preparing the same. The method for preparing the super-hydrophobic coating provided by Comparative Example 2 is substantially the same as the method for preparing the super-hydrophobic coating provided by Example 1, except that no fluorinated nano-SiO2 particles are added in Step 3.

[0063] Comparative Example 3: Comparative Example 3 provides a super-hydrophobic coating with honeycomb micro-porous structure and a method for preparing the same. The method for preparing the super-hydrophobic coating provided by Comparative Example 3 is substantially the same as the method for preparing the super-hydrophobic coating provided by Example 1, except that no two-stage temperature-lifting curing process is performed in Step 5, and the composite slurry is directly sprayed onto the surface of the pretreated substrate.

[0064] Comparative Example 4: Comparative Example 4 provides a super-hydrophobic coating with honeycomb micro-porous structure and a method for preparing the same. The method for preparing the super-hydrophobic coating provided by Comparative Example 4 is substantially the same as the method for preparing the super-hydrophobic coating provided by Example 1, except that no low-temperature fluorosilane vapor deposition process is performed on the honeycomb micro-porous structure coating in Step 6.

[0065] Specifically, the super-hydrophobic coatings provided by Examples 1-11 and Comparative Examples 1-4 are subjected to tensile test, hydrophobic performance test, and coating thickness test, respectively: the elongation at break of the coating film is tested according to the tensile test (ASTM D2370); the contact angle and the rolling angle are used to quantitatively characterize the hydrophobic performance of the coating according to the requirements of GB / T 30693-2014 specification, and the static contact angle is randomly measured at different positions (at least 5 points) on the surface of the coating and the average value is calculated; the thickness of the coating is tested according to the requirements of the national standard GB / T 13452.2-2008 specification, and at least 10 points on the surface of the coating are randomly selected for measurement, and the average value is calculated.

[0066] The performance test results of the super-hydrophobic coatings provided by Examples 1-11 and Comparative Examples 1-4 are shown in Table 1 below:

[0067] Based on the above embodiments and test results, it can be clear that the super-hydrophobic coating with a honeycomb microporous structure and the preparation method thereof provided by the application realize performance optimization through multi-component synergy and process precise control: the core-shell polymer particles act as toughening units, and the soft elastomer core can act as a stress concentration point when stressed, effectively inducing, terminating and dispersing silver streaks, absorbing a large amount of impact energy, and significantly improving the toughness, impact resistance and elongation at break of the coating from the molecular level; the incompatibility between the volatile organic pore-forming agent and the resin system is used, and the micrometer droplet 'template' is formed by high-speed shearing dispersion, the template is volatilized by heating in the low-temperature curing stage, and the regular micrometer honeycomb holes are left in situ, thereby constructing the macro-roughness skeleton required for super-hydrophobicity; the fluorinated nano-SiO2 acts as a rigid nano-unit, providing inherent nano-roughness and extremely low surface energy, and in the pore-forming agent volatilization and resin curing process, it is spontaneously migrated and preferentially enriched on the pore wall and the coating surface driven by the interfacial energy, and is stably anchored in the resin network, thereby forming a stable micro-nano hierarchical structure.

[0068] Specifically, the two-stage stepwise temperature curing process in step five plays a key role: at a lower temperature, the volatile organic pore-forming agent has sufficient time to slowly and completely volatilize, ensuring the complete formation of the honeycomb structure, and the resin is preliminarily gelled, providing a dynamic interface for the migration and enrichment of nanoparticles; after warming up, the epoxy resin and the curing agent are fully and completely crosslinked, the micro-nano hierarchical structure formed previously is completely locked in the highly crosslinked three-dimensional network, and the coating obtains high mechanical strength, durability and chemical stability. The enrichment of fluorinated nano-SiO2 on the surface is the basis for the super-hydrophobicity of the coating, and subsequent low-temperature fluorosilane gas phase deposition treatment grafts more dense and better oriented perfluoroalkyl long chains on the micro-nano rough structure surface, ultimately optimizes and strengthens the surface energy, and further improves the hydrophobic performance and durability.

[0069] As can be seen from Comparative Example 1, Example 2 and Example 3, the greater the mass ratio of the core-shell polymer particles to the water-based epoxy resin (component A) (the more the amount), the more significant the toughening effect, and the more obvious the improvement in the toughness, impact resistance and elongation at break of the coating, and the test results show that the coating prepared in Example 2 has the best toughness.

[0070] As can be seen from Comparative Example 1, Example 4 and Example 5, the more the mass of the volatile organic pore-forming agent, the more abundant the micrometer honeycomb holes left in the coating during the low-temperature curing stage, and the more conducive to constructing the macro-roughness skeleton required for super-hydrophobicity, and the test results show that the coating prepared in Example 4 has the best hydrophobicity.

[0071] As can be seen from Comparative Example 1, Example 6 and Example 7, the higher the mass ratio of the fluorinated nano-SiO2 particles to the water-based epoxy resin (component A), the more sufficient the nano-roughness and low surface energy provided, and the more conducive to improving the hydrophobic properties of the coating.

[0072] From Comparative Example 1, Example 8 and Example 9, it can be seen that the higher the processing temperature of the wet film in the oven and the longer the processing time, the more conducive to providing a dynamic interface for the migration and enrichment of fluorinated nano-SiO2 particles, and the enrichment of the particles on the surface is the basis for the super-hydrophobicity of the coating.

[0073] From Comparative Example 1, Example 10 and Example 11, it can be seen that in the fluorosilane vapor deposition treatment, the higher the amount of fluorosilane and the longer the deposition time, the more conducive to grafting a more dense and better oriented perfluoroalkyl long chain on the micro-nano rough structure surface, optimizing the surface energy and further improving the hydrophobicity and durability. The test results show that Example 11 achieves the highest water contact angle and the lowest rolling angle.

[0074] From Comparative Example 1 and Comparative Example 1, it can be seen that the core-shell polymer particles are mainly used to improve the toughness of the coating. The free elongation of Example 1 is about 43% higher than that of Comparative Example 1, but has little effect on the hydrophobicity.

[0075] From Comparative Example 1 and Comparative Example 2 and Comparative Example 3, it can be seen that the addition amount of fluorinated nano-SiO2 particles and the structure of the honeycomb microstructure can significantly improve the hydrophobicity of the coating, and the water contact angle is increased by about 30%.

[0076] From Comparative Example 1 and Comparative Example 4, it can be seen that after the coating is treated by low-temperature fluorosilane vapor deposition, the water contact angle can be increased by about 10%.

[0077] The present application realizes the construction of micron-level honeycomb holes and the interface enrichment of nano-level low surface energy substances in the epoxy resin matrix by the strategies of "multi-phase synergistic construction" and "step-by-step programmed curing", thereby creating a composite coating with excellent toughness, high adhesion and durable super-hydrophobicity, as follows: The soft elastomer core of the core-shell polymer particle as a toughening unit can effectively induce, terminate and disperse the silver streaks when stressed, absorb a large amount of impact energy, the hard polymer shell layer has good compatibility with the epoxy resin matrix, and the stress can be effectively transmitted, so that the toughness, impact resistance and elongation at break of the coating are greatly improved at the molecular level. By using the incompatibility of the volatile organic pore-forming agent and the resin system, the pore-forming agent is dispersed into uniform micrometer-sized droplets by high-speed shearing to form a "template", and the "template" is volatilized by heat in the low-temperature curing stage, leaving a regular micrometer-sized honeycomb hole in situ, and a macroscopic roughness skeleton required for superhydrophobicity is constructed. The fluorinated nano-SiO2 particles as rigid nano units provide inherent nanoscale roughness and extremely low surface energy. During the volatilization of the pore-forming agent and the curing of the resin, the particles spontaneously migrate and preferentially enrich on the pore wall and the coating surface under the driving of interfacial energy, and are stably anchored in the resin network, forming a stable micro-nano hierarchical structure. At a relatively low temperature, the pore-forming agent has enough time to slowly and completely volatilize, ensuring the complete formation of the honeycomb structure. At the same time, the resin is preliminarily gelled at this stage, providing a dynamic interface for the migration and enrichment of the nanoparticles, but the viscosity is sufficient to allow the structure to adjust. The increase in temperature allows the epoxy resin and the curing agent to fully and completely crosslink. This process completely "locks" the micro-nano hierarchical structure formed in the previous stage in the highly crosslinked three-dimensional network, so that the coating obtains the final high mechanical strength, durability and chemical stability. The fluorinated nano-SiO2 particles themselves have extremely low surface energy, and their enrichment on the surface is the basis for the superhydrophobicity of the coating. Subsequent low-temperature fluorosilane gas deposition treatment grafts more dense and better oriented perfluoroalkyl long chains on the micro-nano rough structure surface, optimizes and strengthens the surface energy, and further improves the hydrophobicity and durability.

[0078] In summary, the present application makes the micro-pore construction, nano-enhancement, toughness toughening and low surface energy modification function modules synergistically act through the ingenious component design and strict process control, and finally forms a multifunctional superhydrophobic protective coating with stable structure and long-lasting function on the substrate. The superhydrophobic coating with a honeycomb micro-pore structure and the preparation method thereof provided by the present application can be used in the fields of ice prevention, corrosion prevention, oil stain prevention and liquid prevention of various substrates (concrete, bridge ropes, etc.).

[0079] Compared with the prior art, the present application has at least the following advantages: First, the soft core of the core-shell polymer particles selected by the present application can effectively induce silver streaks, cavitation and shear bands, absorb a large amount of impact energy, and the hard shell with good compatibility with the matrix ensures effective stress transfer, greatly improving the impact strength and elongation at break of the coating; at the same time, the introduction of fluorinated nano-SiO2 particles and the construction of the honeycomb-like microporous structure greatly improve the hydrophobic properties of the coating, making the coating have excellent toughness and super-hydrophobic properties.

[0080] Second, the present application uses a volatile pore-forming agent to spontaneously volatilize and form pores during the low-temperature curing stage, eliminating the cumbersome template removal step (such as water washing, acid etching, etc.) in the template method, simplifying the process flow and improving production efficiency; through two-stage stepwise temperature curing, pore formation is followed by deep crosslinking. The pore-forming agent volatilizes to naturally form a micron-level honeycomb structure, while the fluorinated nano-SiO2 particles spontaneously migrate and enrich, building a firm micro-nano hierarchical structure; the final high-temperature curing fully crosslinks the resin, "locking" the structure, and the hydrophobic properties, strength and durability of the coating are significantly better than those of a simple blending system.

[0081] Third, in the super-hydrophobic coating provided by the present application, the fluorinated nano-SiO2 particles enriched on the surface of the coating provide persistent low surface energy, which cooperates with the honeycomb-like microstructure to endow the coating with outstanding and stable super-hydrophobic properties; this method can be used for various substrates (concrete, bridge ropes, etc.), and the coating method is flexible and easy to implement large-scale application.

[0082] It should be noted that each of the above embodiments belongs to the same inventive concept, and each embodiment has its own emphasis in description. If not fully described in an individual embodiment, reference can be made to the description in other embodiments.

[0083] The above embodiments only express the implementation of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the scope of protection of the present patent should be subject to the appended claims.

Claims

1. A method for producing a superhydrophobic coating having a honeycomb-like microporous structure, characterized by, The preparation method comprises the following steps: S10, mixing the core-shell polymer particles with the aqueous epoxy resin and then performing shearing treatment to obtain a suspension; S20, mixing the suspension with a volatile organic pore-forming agent, uniformly dispersing the mixture by stirring to obtain an emulsion; S30, mixing the emulsion, fluorinated nano-SiO2 particles and a dispersing agent, and then performing shearing treatment to obtain a suspension slurry; S40, mixing the suspension slurry with an epoxy resin curing agent in a proper proportion, and then uniformly stirring to obtain a composite slurry; S50, spraying the composite slurry on the surface of a pretreated substrate, and then performing two-stage temperature rising curing to volatilize the volatile organic pore-forming agent and promote resin crosslinking, so as to form a honeycomb micro-porous structure coating; S60, performing fluorosilane vapor deposition treatment on the honeycomb micro-porous structure coating to obtain an ultrahydrophobic coating with a honeycomb micro-porous structure.

2. The method for preparing a superhydrophobic coating having a honeycomb micro-porous structure according to claim 1, characterized in that, In the step S10, the core-shell polymer particles have a core-shell structure, the core is an acrylate copolymer elastomer, and the shell is one of polymethyl methacrylate or an acrylate polymer containing an epoxy functional group; and the average particle size of the core-shell polymer particles is 100-500 nm.

3. The method for preparing a superhydrophobic coating having a honeycomb micro-porous structure according to claim 2, characterized in that, In the step S10, the mass ratio of the core-shell polymer particles to the aqueous epoxy resin is 1:(10-20).

4. The method of claim 1, wherein the method further comprises the step of: 5 applying a second layer of a hydrophobic material to the surface of the substrate. In the step S20, the volatile organic pore-forming agent comprises an organic solvent with a boiling point of 50-120℃, the organic solvent comprises at least one of butyl acetate, acetone and ethyl acetate; and the mass ratio of the suspension to the volatile organic pore-forming agent is (5-20):

1.

5. The method of claim 1, wherein the method further comprises the step of: 5-1) applying a second solution to the substrate to form a second layer of the superhydrophobic coating on the substrate, wherein the second solution comprises a second solvent and a second hydrophobic material, and the second hydrophobic material is different from the first hydrophobic material. The fluorinated nano-SiO2 particles in the step S30 are hydrophobic fumed silica surface-modified by heptadecafluorodecyltriethoxysilane, with an average particle size of 7-40 nm, a specific surface area of 150-300 m 2 / g, with an addition amount of 3-6% of the mass of the waterborne epoxy resin; the dispersant is a high-molecular-weight super dispersant of BYK-154 type, with an addition amount of 20-60% of the mass of the fluorinated nano-SiO2 particles.

6. The method of claim 2, wherein the method further comprises the step of: 5 applying a second layer of the hydrophobic material on the first layer of the hydrophobic material. In the step S40, the molar ratio of active hydrogen in the epoxy resin curing agent to the epoxy group in the aqueous epoxy resin is (0.8-1.2):

1.

7. The method for preparing a superhydrophobic coating with a honeycomb microporous structure according to claim 1, characterized in that, In the step S50, the substrate comprises at least one of concrete and bridge ropes, and the pretreatment of the substrate comprises polishing, cleaning and drying in sequence.

8. The method of claim 1, wherein the method further comprises the step of: 8-1) applying a second solution to the substrate to form a second layer of the superhydrophobic coating on the substrate, wherein the second solution comprises a second solvent and a second hydrophobic material, and the second hydrophobic material is different from the first hydrophobic material. The step S50 specifically comprises: S501, placing the pretreated substrate sprayed with the composite slurry in an oven, heating at 60-80℃ for 20-60 min; S502, increasing the temperature of the oven to 115-125℃, and then heating and curing for 1-3 h to obtain the honeycomb micro-porous structure coating.

9. The method of claim 1, wherein the method further comprises the step of: 9-1) applying a second solution to the substrate to form a second layer of the superhydrophobic coating on the substrate, wherein the second solution comprises a second solvent and a second hydrophobic material, and the second hydrophobic material is different from the first hydrophobic material. The step S60 specifically comprises: Performing perfluorodecyltriethoxysilane vapor deposition treatment on the honeycomb micro-porous structure coating; wherein the amount of perfluorodecyltriethoxysilane is 50-200 μL based on a closed container with a volume of 1-2 L, the purity is ≥95%, the deposition temperature is controlled to be 90-100℃, and the deposition time is 2-4 h.

10. A superhydrophobic coating having a honeycomb-like microporous structure, characterized in that, The ultrahydrophobic coating with a honeycomb micro-porous structure is prepared by the preparation method of the ultrahydrophobic coating with a honeycomb micro-porous structure according to any one of claims 1-9.

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