Graphene low-surface-energy coating and preparation method thereof

Abstract

The invention relates to a graphene low-surface-energy coating and a preparation method thereof.The coating is composed of a component A and a component B. The component A comprises polysiloxane resin, graphene slurry, super-hydrophobic powder, a defoaming agent, a dispersing agent and other raw materials, and the component B is a mixture of an aliphatic isocyanate curing agent and butyl acetate. The graphene is combined with the polysiloxane resin to form an efficient low-surface-energy coating, so that the hydrophobicity and the icing resistance of the coating are remarkably improved. The graphene slurry is used as a key component, and the super-hydrophobicity of graphene is combined with the weather resistance and aging resistance of polysiloxane resin through reasonable proportioning and a fine process, so that various properties of the coating are further optimized. The coating shows good secondary coating adhesive force and durability in the application process, is especially suitable for the fields of aviation, navigation, high-altitude electric wires, meteorological equipment and the like, and can effectively prolong the service life of the equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-performance coatings, and particularly relates to a graphene low-surface-energy coating and a preparation method thereof. BACKGROUND

[0002] With the development of science and technology, super-hydrophobic materials have shown great application potential in anti-icing, waterproofing, anti-fouling and corrosion resistance, etc. Especially in some special fields such as aerospace, marine equipment and power transmission systems, icing often leads to equipment damage, accidents, and even threatens personnel safety in severe cases. Traditional anti-icing methods include mechanical deicing, electric heating deicing and chemical deicing, but these methods often have the disadvantages of low efficiency, high energy consumption, environmental pollution, etc., and cannot provide long-term stable protection in harsh environments. Therefore, the research on anti-icing coatings has become an important topic in the field of coatings.

[0003] Existing super-hydrophobic coating technologies mostly rely on constructing micro-nano structures on the surface of the substrate to achieve super-hydrophobic effect. These coatings usually have low surface energy, so that water droplets form a contact angle greater than 150° on the surface, thereby achieving the effect of waterproofing and anti-icing. However, traditional super-hydrophobic coatings often face problems such as weak coating, poor durability, weak adhesion in secondary coating, etc. This is because the super-hydrophobic surface gradually loses its hydrophobicity when subjected to external force or exposed to harsh environments for a long time, thereby reducing the effect of the coating. Especially in cold regions, the super-hydrophobic coating is easily damaged under the influence of multiple icing and melting cycles, resulting in rapid decline in coating performance.

[0004] In view of these problems, graphene, as a new type of carbon-based nanomaterial, has attracted widespread attention due to its excellent mechanical properties, thermal stability and chemical stability. Graphene not only has excellent electrical conductivity and thermal conductivity, but also has low surface energy, which makes it have great application potential in coatings. Studies have shown that the introduction of graphene into coatings can effectively improve the anti-icing performance and aging resistance of the coatings. However, as a single modifier, graphene has poor dispersibility and uniformity, which can easily lead to unstable and uneven coating performance. SUMMARY

[0005] One purpose of the present application is to provide a graphene low-surface-energy coating and a preparation method thereof. The present application uses graphene as a modifier combined with polysiloxane resin to prepare a graphene low-surface-energy coating.

[0006] To achieve the above purpose, the first aspect of the present application provides a graphene low-surface-energy coating, which comprises component A and component B, wherein: The component A is composed of the following raw materials in parts by mass: polysiloxane resin 400-600 parts; graphene slurry 80-150 parts; super-hydrophobic powder 100-150 parts; dispersant 5-15 parts; antifoaming agent 5-10 parts; organobentonite 5-15 parts; polyamide wax slurry 10-25 parts; titanium white powder 80-120 parts; organic solvent 100-150 parts; The B component comprises the following raw materials in parts by mass: aliphatic isocyanate curing agent 700-900 parts, butyl acetate 150-250 parts.

[0007] Further, the graphene slurry comprises the following raw materials in parts by mass: graphene 80-120 parts, dispersant 150-250 parts, polysiloxane resin 300-500 parts, organobentonite 30-60 parts, and solvent 200-300 parts.

[0008] Further, the solvent is butyl acetate.

[0009] Further, the organic solvent is a mixture of propylene glycol methyl ether acetate, butyl acetate, and xylene.

[0010] Further, the polysiloxane resin is a hydroxyl-terminated or methyl-terminated polysiloxane resin.

[0011] Further, the dispersant is a high-molecular block copolymer containing a pigmentophilic group and a binary fat, in a mass ratio of 1:1.

[0012] Further, the antifoaming agent is a non-silicon polymer or an acrylate copolymer.

[0013] Further, the super-hydrophobic powder is a polytetrafluoroethylene powder with a particle size of 5-10 μm.

[0014] Further, the present application also provides a preparation method of the graphene low-surface-energy coating, comprising the following steps: Preparation of graphene slurry: graphene, dispersant, polysiloxane resin, organobentonite, and butyl acetate are sequentially added, uniformly mixed at low speed, then dispersed at a speed of 1200 r / min for 20 min, and finally ground to a fineness of less than 15 μm to obtain the graphene slurry; Preparation of A component: add the polysiloxane resin, graphene slurry, super-hydrophobic powder, dispersing agent, defoaming agent, organic bentonite, polyamide wax slurry, titanium white powder and organic solvent in sequence, disperse at high speed for 20 minutes under cooling condition, filter after grinding to fineness less than 20 μm, to obtain A component; Preparation of B component: mix and stir the aliphatic isocyanate and butyl acetate uniformly to obtain B component; After mixing and uniformly mixing A component and B component in sequence, the coating is obtained.

[0015] Further, the water contact angle of the coating is 148°-155°, and the aging resistance is 2100-2280 h.

[0016] The embodiments of the present application have the following technical effects: (1) The present application introduces graphene slurry into the low surface energy coating system, so that the coating has super-hydrophobic performance far beyond traditional materials, thereby significantly improving the anti-icing effect and the ability to resist environmental wetting erosion. The present application utilizes the characteristics of graphene itself, i.e. extremely low surface energy and high hydrophobicity, to make the coating obtain stable and durable hydrophobicity. At the same time, compared with the traditional method relying on powder accumulation, the present application further constructs a micro-nano double-scale rough interface through the two-dimensional layered structure of graphene, so that the water droplets almost roll in a spherical state, greatly reducing the contact area and residence time of water droplets with the substrate surface, thereby effectively blocking the ice crystal formation conditions and improving the anti-icing performance. In addition, the sheet structure of graphene forms a continuous protective barrier in the coating, which not only enhances the hydrophobicity but also has a certain heat blocking effect, which can delay the cold and hot exchange and further delay the initial time of icing.

[0017] (2) The present application replaces part of the hydrophobic powder with graphene and introduces high-performance polysiloxane resin as a film-forming material, so that the solid content of the product is significantly increased to about 68%~70%, and the film thickness after one coating is more than 60 μm, which fundamentally breaks through the limitation of traditional low surface energy coatings that cannot be thickly coated. The improvement of thick coating performance not only means that the coating has better mechanical strength and durability, but also increases the ability of the coating to resist external wear and erosion, avoiding the risk of water vapor penetration and failure due to local damage. The micro-enhanced network structure of graphene in the coating further improves the scratch resistance, crack resistance and adhesion of the coating, so that the thick coating structure can still maintain the integrity of the coating without cracking or peeling problems.

[0018] (3) The present application realizes the significant enhancement of the stability of the coating in long-term outdoor environment on the basis of the traditional low surface energy coating system by using polysiloxane resin as the main film-forming base material and combining the special anti-aging performance of graphene, thereby overcoming the inherent defects of the short service life and easy failure of the existing super-hydrophobic coating. The polysiloxane resin has excellent heat resistance, ultraviolet radiation resistance and weather resistance, and a large number of stable Si-O bonds exist in the main chain structure, so that the coating can be exposed to high-intensity ultraviolet light, humidity and heat cycle and ozone environment for a long time without obvious aging or structure decomposition. At the same time, the graphene sheet structure forms a shielding layer effect in the coating, significantly slows down the erosion speed of oxygen, water and polar ions to the coating matrix, and improves the overall anti-aging performance. The excellent anti-aging performance not only ensures that the coating maintains long-term hydrophobic function during the service period, but also effectively improves the corrosion resistance and prevents the corrosion of the substrate due to aging cracks. In addition, the reasonable combination of antioxidants, ultraviolet absorbers and other additives further inhibits the free radical cracking reaction, so that the coating shows stable performance in strong ultraviolet or extreme temperature impact environment. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the embodiments of the present application. The following embodiments are used to explain the present application, but not to limit the scope of the present application.

[0020] Those skilled in the art should understand that the embodiments described below are only a part of the embodiments of the present application, but not all the embodiments of the present application, and the part of the embodiments are intended to explain the technical principles of the present application, but not to limit the protection scope of the present application. Based on the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the protection scope of the present application.

[0021] The present application provides a graphene low surface energy coating, which comprises A component and B component, wherein: The A component is composed of the following raw materials in parts by mass: Polysiloxane resin 400-600 parts; Graphene slurry 80-150 parts; Super-hydrophobic powder 100-150 parts; Dispersing agent 5-15 parts; Defoaming agent 5-10 parts; Organic bentonite 5-15 parts; Polyamide wax slurry 10-25 parts; Titanium dioxide 80-120 parts; Organic solvent 100-150 parts; The B component includes the following mass parts of raw materials: aliphatic isocyanate curing agent 700-900 parts, butyl acetate 150-250 parts.

[0022] The present application introduces graphene paste into the polysiloxane resin system, combines with super-hydrophobic powder and a specific auxiliary system, regulates the surface energy, curing network structure and interfacial bonding force of the coating from the molecular structure level, thereby realizing the comprehensive improvement of hydrophobicity, anti-icing property, aging resistance, thick coating property and excellent adhesion. The polysiloxane resin is an inorganic-organic hybrid polymer with Si-O-Si as the main chain structure, which has high chemical bond energy and bond angle, so that the main chain has high flexibility and heat stability. The side groups of polysiloxane molecules usually contain a large number of hydrophobic groups such as methyl, ethyl or fluoroalkyl groups. These non-polar groups determine that the surface energy is very low, usually less than 20 mN / m, thereby forming a natural waterproof property. However, a single polysiloxane coating has insufficient mechanical strength due to the excessively large flexibility of the molecular chain and weak van der Waals force, which leads to problems such as chain segment rupture, surface energy migration or aging and powdering under external stress, ultraviolet radiation and thermal oxidation conditions. Traditional methods usually improve the strength and hydrophobicity of the coating by filling inorganic nano-powder, but this pure physical compounding method has problems such as poor dispersion of fillers, insufficient interfacial compatibility and particle precipitation after long-term service, which ultimately makes the coating lose the low surface energy property and limits the durability.

[0023] Therefore, the present application introduces graphene into the raw material system, thereby significantly reducing the surface energy of the coating while reducing the hydrophobic property. Graphene is a single-atom layer two-dimensional crystal structure material composed of carbon atoms in sp 2 hybrid mode, which has a very high specific surface area, excellent mechanical properties, thermal and electrical conductivity, and unique surface energy characteristics. The introduction of graphene into the coating system not only significantly improves the mechanical strength, thermal stability and corrosion resistance of the coating, but more importantly, it plays a role in surface micro-nano structure regulation and surface energy adjustment, making the coating exhibit excellent hydrophobic property. The surface of the graphene sheet is mainly composed of carbon six-membered rings, and there are almost no polar functional groups, so its surface energy is much lower than that of general organic polymers or inorganic fillers. This low surface energy property itself makes graphene itself have a natural hydrophobic tendency. When graphene is uniformly dispersed and exposed on the surface of the coating, it forms a non-polar barrier layer with carbon-carbon bonds at the interface, thereby effectively reducing the surface free energy of the entire coating. The lower the surface energy, the worse the spreading ability of the liquid droplet on it, and the larger the contact angle. Therefore, by introducing graphene, the present application can reduce the potential energy of the interaction between the coating and water from the chemical composition level, so that water molecules are difficult to form stable hydrogen bond adsorption or polarity on the surface, thereby realizing the hydrophobic effect.

[0024] Further, the graphene sheet surface has excellent rigidity and chemical stability, so that the micro-nano structure can maintain high integrity and durability under external friction, erosion or temperature change conditions. Unlike traditional low surface energy organic modifiers, this graphene-based rough structure is physically constructed rather than simply chemically bonded, so it is not prone to decomposition, migration or aging during long-term service. The high modulus and high strength characteristics of graphene can also prevent cracks from occurring in the coating during curing shrinkage, thereby maintaining the continuity of the hydrophobic structure. In addition, graphene and the matrix resin can be connected by π-π interaction or van der Waals force, thereby further improving the stability of the structure.

[0025] Further, the graphene slurry includes the following raw materials: graphene 80-120 parts, dispersant 150-250 parts, polysiloxane resin 300-500 parts, organic bentonite 30-60 parts, and solvent 200-300 parts.

[0026] In the coating of the present application, graphene serves as the main functional phase, and its intrinsic properties are the core source of realizing low surface energy and hydrophobic properties of the coating. The graphene surface is formed by the close arrangement of carbon six-membered rings, which has a sp 2 Hybrid structure, so that its surface contains almost no polar groups, showing extremely low surface energy and excellent hydrophobicity. However, there is strong π-π interaction and van der Waals force between graphene sheets, which is prone to agglomeration, thereby affecting the dispersion stability and uniformity in the coating. Therefore, in the coating system of the present application, the graphene is pretreated into a slurry, and a high proportion of dispersant and polysiloxane resin is introduced into the slurry, and organic bentonite is used as a space network stabilizing structure, realizing effective peeling, coating and stabilization of the graphene sheet. Through the synergistic effect of multiple components, efficient dispersion and stable distribution of graphene are realized, thereby laying the foundation for the coating system to have excellent hydrophobicity, low surface energy and durability. The graphene slurry is not only a single physical dispersion, but also a stable dispersion system formed by the coupling of interfacial chemistry and rheological structure, and its structure and interfacial state directly determine the role of graphene in the subsequent coating system.

[0027] The dispersant plays a crucial role in the interface regulation in the slurry system. The dispersant mass fraction is 150-250 parts, which is much higher than the amount of graphene. This is because the dispersant molecules contain hydrophobic segments that can form π-π interaction or hydrophobic interaction with the surface of graphene, which can be firmly adsorbed on the surface of graphene sheet, thereby forming an effective spatial isolation layer between graphene; at the same time, the dispersant molecules contain resinophilic segments or polar groups that are compatible with polysiloxane resin and solvent, thereby forming a thermodynamically stable interface layer in the slurry. This "carbonophilic-resinophilic" amphiphilic structure enables graphene to be uniformly dispersed in the slurry in the form of single-layer or few-layer sheets, and to exhibit good flowability and uniformity in the entire coating system.

[0028] The addition of polysiloxane resin in the graphene slurry not only serves as a dispersion medium, but more importantly, as a synergistic construction material for structure and interface. The polysiloxane molecular backbone is composed of Si-O-Si bonds, and the side chains can have non-polar substituents such as methyl and ethyl groups. It has extremely low surface energy and excellent flexibility and thermal stability. After the polysiloxane forms a coating film on the surface of graphene, it can physically prevent the re-aggregation of the sheet and chemically reduce the surface energy of the system. When the slurry is introduced into the final coating, this coating structure is still retained, enabling graphene and polysiloxane to form a low-energy interface layer on the surface of the coating. More importantly, the polysiloxane resin will orient and arrange at the interface during the curing process, with its methyl or organic segments facing the air phase, thereby forming a surface with extremely low energy, significantly improving the hydrophobicity.

[0029] The introduction of organic bentonite in the slurry plays a role in adjusting the rheological properties and preventing sedimentation, and can form a composite sheet network with graphene. This three-dimensional network structure microscopically restricts the free movement of graphene sheets, enabling the slurry to have good thixotropy and energy storage characteristics. The network can also absorb external shear force during grinding and dispersion, preventing excessive fragmentation of graphene sheets, while improving the stability and workability of the slurry. In addition, the polar interlayer surface of the organic bentonite can interact weakly with the polysiloxane molecular chain, further improving the overall uniformity of the system.

[0030] In summary, graphene provides a low surface energy basis as a hydrophobic functional phase, dispersant provides interface compatibility and stability, polysiloxane resin constructs a low-energy barrier and enhances interface bonding, organic bentonite forms a thixotropic network to stabilize the system, and solvent serves as a transfer medium to optimize the rheological properties and dispersion state. The five components work together through chemical adsorption, physical coating, and steric hindrance during grinding and dispersion to achieve high dispersion and stable suspension of graphene sheets in the system, ultimately ensuring that the coating can form a continuous and uniform low-energy surface after film formation.

[0031] Further, the solvent is butyl acetate.

[0032] Butyl acetate is a medium-polar ester solvent, which contains both carbonyl group capable of weak interaction with polar substances and long butyl carbon chain, thus possessing certain lipophilicity and non-polarity characteristics. Such molecular structure enables it to have compatibility with organic polymers and part of inorganic layered substances, showing excellent dissolving and dispersing performance. In the graphene paste system of the present application, the polarities of graphene, dispersant, polysiloxane resin and organic bentonite and other components are quite different. If the polarity of the solvent is too strong, it will destroy the π-π stacking balance on the surface of graphene, leading to curling or agglomeration of the sheet. If the polarity of the solvent is too weak, it is also difficult to effectively wet and disperse organic bentonite or dispersant. Therefore, butyl acetate as a medium-polar solvent between polarity and non-polarity can play the role of "polarity coordinator" in the graphene system, so that the components achieve thermodynamic compatibility and kinetic stable balance at the molecular level.

[0033] Further, the organic solvent is a mixture of propylene glycol methyl ether acetate, butyl acetate and xylene.

[0034] Specifically, propylene glycol methyl ether acetate as a solvent with medium polarity can effectively dissolve polysiloxane resin and some hydrophobic compounds, and at the same time has lower volatility, which enables it to maintain stable dispersion effect in the solution for a long time, avoiding the agglomeration of graphene and other components during the preparation of the coating. The addition of propylene glycol methyl ether acetate not only optimizes the performance of the dispersant, but also improves the dispersion uniformity of graphene, avoiding the problem of uneven coating film quality caused by the agglomeration of graphene particles. Its high solubility is particularly suitable for resin systems, which can maintain good stability of the solvent and ensure the consistency of the coating during construction.

[0035] Secondly, butyl acetate as a solvent plays the role of flow adjustment and stable dispersion in the present application. Butyl acetate has a low solubility parameter, which enables graphene to maintain good dispersibility in the resin. Butyl acetate has moderate volatility, which can better control the evaporation rate of the coating during drying, avoiding uneven surface or bubbles caused by too fast drying. Through the introduction of butyl acetate, the construction performance of the coating is greatly improved, not only enhancing the adhesion of the coating on different surfaces, but also improving the uniformity and density of the coating, so that the coating forms a smoother and more uniform surface, thereby enhancing the functionality of the coating, such as water resistance, corrosion resistance, etc.

[0036] In addition, as an aromatic hydrocarbon solvent, xylene mainly enhances the volatilization performance of the solvent system in coatings. Xylene has a high volatilization rate, which helps to accelerate the drying speed of the coating layer, especially in large-area coating, which can effectively avoid the problems of sagging, flow marks and other problems caused by excessive wetness. Xylene can also effectively reduce the viscosity of the coating and improve its flowability, providing better coating performance during the coating process and ensuring that the coating can uniformly cover the desired surface. In addition, xylene has a regulating effect on the overall physical and chemical properties of the organic solvent system, which can effectively control the workability of the coating and the adaptability of the construction environment. By reasonably adjusting the ratio of propylene glycol methyl ether acetate, butyl acetate and xylene, the quality of the coating layer can be guaranteed while meeting the needs of different construction conditions.

[0037] Further, the polysiloxane resin is a hydroxyl-terminated or methyl-terminated polysiloxane resin.

[0038] Specifically, the polysiloxane resin is a silicone polymer with Si-O-Si as the main chain structure, and its bond energy is as high as 451 kJ / mol, much higher than that of general C-C and C-O bonds, thus having extremely high thermal stability and chemical inertness. The flexible chain structure and low-polarity methyl substituent of polysiloxane endow it with excellent low surface energy properties, making it an ideal resin material for preparing functional coatings such as waterproof, anti-icing and antifouling. However, the inertness of polysiloxane itself also brings certain limitations, such as difficulty in chemical bonding with other components, weak adhesion of the coating layer, limited crosslinking strength, etc. To solve these deficiencies, the hydroxyl-terminated or methyl-terminated polysiloxane resin selected by the present application is finely controlled in terms of the chemical structure of the end group, taking into account the reactivity and low surface energy properties, thereby achieving a balance between chemical crosslinking and performance stability in the system.

[0039] The end group of the hydroxyl-terminated polysiloxane is -Si-OH, which has certain reactivity and can react with the -NCO group in the isocyanate curing agent to form a stable chemical crosslinking structure in the coating curing process. This crosslinking not only enhances the mechanical strength and adhesion of the coating, but also chemically connects the flexible chain of the polysiloxane with the graphene sheet layer, realizing the chemical integration of the organic and inorganic phases. At the same time, the presence of the hydroxyl-terminated group is also conducive to the formation of hydrogen bonds or condensation reactions with some oxygen-containing functional groups in the graphene paste, thereby enhancing the bonding force of the two-phase interface and improving the dispersion stability and structural density of the coating. On the other hand, methyl-terminated polysiloxane mainly constructs a low-surface-energy interface through its high-density -CH3 substituent group, making the coating have extremely strong hydrophobicity and anti-pollution performance after curing. The non-polar characteristics and spatial orientation effect of the methyl substituent group make it easy to migrate to the surface of the coating, and spontaneously form a methyl-rich outer layer during film formation, thereby significantly reducing the surface free energy of the coating and improving the contact angle to near super-hydrophobic level. The synergistic use or preferential selection of the two termination methods enables the coating to have good chemical reactivity to ensure crosslinking strength, and also maintain ultra-low surface energy to achieve high-level hydrophobicity.

[0040] Specifically, the polysiloxane resin used in the present application is PL2075 type polysiloxane resin. It is a high-end material commonly used in the industry for weather-resistant and protective coatings, which contains an appropriate amount of hydroxyl end groups in its molecular structure, and the main chain flexibility is moderate, which can react with aliphatic isocyanate to form a crosslinked network during curing. Compared with ordinary methyl silicone resin, PL2075 has higher solid content and better rheological properties, so it can still maintain excellent flatness and adhesion in thick coating applications. Especially in the system of the present application, graphene and super-hydrophobic powder coexist, and the viscosity of the system is high. If the resin flowability is insufficient, it will cause construction difficulty and coating defects. The molecular weight distribution and viscosity characteristics of PL2075 can provide good workability, so that graphene and other components are uniformly distributed in the system and form a dense continuous phase during curing.

[0041] In the graphene modified system, the polysiloxane resin not only serves as a matrix material, but also has an interface synergistic effect with graphene. The hydroxyl-terminated polysiloxane can form a hydrogen bond network with the graphene paste during dispersion, making the graphene sheet layer more stable, and the urethane structure formed by the reaction of the hydroxyl end group with isocyanate during curing provides new polar points for the system, enhancing the chemical adhesion of the coating to the metal or composite substrate. This "interface chemical bridging" mechanism not only makes the coating excellent in water resistance, ice resistance and other properties, but also significantly improves the wear resistance, weather resistance and anti-peeling performance.

[0042] Further, the dispersant is a mixture of a high-molecular block copolymer containing a pigmentophilic group and a binary fat, with a mass ratio of 1:1; and the defoaming agent is a non-silicon polymer or an acrylate copolymer.

[0043] Specifically, the dispersant used in the coating of the present application is a mixture of a high-molecular block copolymer containing a pigmentophilic group and a binary fat, with a mass ratio of 1:1; and the defoaming agent is a non-silicon polymer or an acrylate copolymer.

[0044] Specifically, the high-molecular block copolymer containing a pigmentophilic group in the dispersant is an interfacial active molecule with obvious amphiphilic properties. The molecular structure of this type of dispersant usually contains two or more chemical composition regions, one of which is a inorganic pigmentophilic group that can be firmly adsorbed on the surface of the graphene sheet through polar interaction, hydrogen bonding or π-π interaction; the other is a flexible chain segment that can freely stretch in the organic phase of polysiloxane resin, propylene glycol methyl ether acetate and butyl acetate, etc., thereby building an interfacial layer with a smooth energy gradient transition between graphene and organic resin. The advantage of this block structure is that it has both "anchoring" and "dissolving" functions, on the one hand, the graphene surface is covered with organic chain segments, avoiding direct stacking and agglomeration between the sheets; on the other hand, compatibility with the organic system is achieved through intermolecular forces, improving the dispersion stability of the coating during storage, application and curing. Compared with traditional low-molecular surfactants, high-molecular block copolymer dispersants have higher molecular weight and longer flexible chain segments, and the steric hindrance effect of the adsorption layer on the graphene surface is stronger, which is not easy to desorb during shearing or heat curing, thereby ensuring the long-term dispersion stability of graphene in the system.

[0045] The binary fat used in conjunction with it plays a synergistic stabilizing role in the system. Binary fat usually has a long alkyl chain and double carboxyl or hydroxyl end groups, which can form a hydrogen bond or van der Waals force complex structure with the high-molecular block copolymer, and on the other hand, can form a fluid lubricating layer at the interface between the graphene sheet and the resin, reducing the interlayer friction and interfacial energy, thereby further improving the dispersion uniformity and fluidity of the system. The binary fat and the high-molecular block copolymer are used in a mass ratio of 1:1, which can form a stable composite adsorption layer structure in the system, which has both the spatial stability of the high-molecular adsorption layer and the flexibility of the low-molecular fat.

[0046] Further, the super-hydrophobic powder is a polytetrafluoroethylene powder with a particle size of 5-10 μm.

[0047] Specifically, the application further improves the hydrophobic performance of the coating by synergistically using graphene and super-hydrophobic powder. The super-hydrophobic powder is polytetrafluoroethylene powder, which belongs to a high-performance hydrophobic filler system. As a high polymer material with extremely low surface energy, excellent chemical inertness and weather resistance, the introduction of polytetrafluoroethylene into the coating system, together with graphene and polysiloxane resin, significantly improves the hydrophobicity and long-term stability of the coating. The polytetrafluoroethylene molecular chain is composed of carbon-carbon backbone and perfluorinated substituent groups, and the surface is almost completely covered by fluorine atoms with high electronegativity. The C-F bond energy between fluorine atoms and carbon atoms is very high, reaching 485 kJ / mol, which not only gives the material excellent chemical inertness and thermal stability, but also makes the surface energy extremely low, much lower than that of common organic polymers. Therefore, when the polytetrafluoroethylene powder is dispersed in the coating system, its surface characteristics can effectively reduce the surface free energy of the entire system, making it difficult for water molecules to form stable hydrogen bond combinations or polar adsorption on the surface of the coating, thereby achieving significant improvement in hydrophobicity. It is worth noting that the polytetrafluoroethylene powder does not completely embed in the matrix during film formation, but slightly floats on the surface due to its low density and surface energy difference when the coating is cured. This interfacial migration effect causes the enrichment of polytetrafluoroethylene particles on the surface of the coating, further reducing the surface energy and enhancing the hydrophobic effect. At the same time, the two-dimensional sheet structure of graphene and the spherical morphology of polytetrafluoroethylene particles interpenetrate to form a network support structure, enhancing the mechanical stability and anti-peeling performance of the coating. The inertness of the surface of polytetrafluoroethylene can also physically block the penetration path of water vapor and oxygen, thereby improving the corrosion resistance and weather resistance of the coating, so that it can maintain hydrophobic properties and gloss in high temperature, high humidity and ultraviolet radiation environments for a long time.

[0048] On the other hand, the fluorine atoms on the surface of the polytetrafluoroethylene powder are regularly arranged, and the electron cloud density is uniformly distributed, which can form an extremely smooth energy potential field at the microscale, promoting water droplets to assume an almost ideal state when they contact the surface, i.e. the droplets only contact a small number of solid protrusions, and the rest are supported by an air layer, thereby achieving super-hydrophobic effect. If the particle size is too large, the particles will not be evenly distributed on the surface of the coating, which will result in high surface roughness of the film layer, and the smoothness of the coating will decrease, and even local mechanical weaknesses will be formed, affecting the adhesion and wear resistance; if the particle size is too small, the particle spacing is insufficient, and an effective air retention space cannot be formed, resulting in a significant decrease in surface hydrophobicity.

[0049] More importantly, although the polytetrafluoroethylene powder is an inert material, in the coating system of the present application, the polysiloxane resin, the organic bentonite and the graphene slurry coexist and can jointly play the role of interface wetting and physical embedding. The polysiloxane molecules have high flexibility and certain non-polar characteristics, and can form physical coating or segment entanglement on the surface of the polytetrafluoroethylene powder particles, thereby enhancing the bonding force between the particles and the matrix; the graphene sheet layer forms a composite network with the polysiloxane through π-π interaction, providing a uniform support base for the polytetrafluoroethylene powder; the organic bentonite limits the migration and sedimentation of the particles through the layered network, so that the particles are uniformly distributed in the system. The multi-component synergistic effect ensures that the polytetrafluoroethylene powder particles remain uniformly distributed and the interface is stable during the curing process of the coating, thereby forming a continuous, dense and micro-undulating low-energy surface.

[0050] Further, the present embodiment also provides a preparation method of the graphene low surface energy coating, comprising the following steps: Preparation of graphene slurry: graphene, dispersant, polysiloxane resin, organic bentonite and butyl acetate are sequentially added, uniformly mixed at low speed, then dispersed at a speed of 1200 r / min for 20 min, and ground to a fineness of less than 15 μm to obtain the graphene slurry; Preparation of component A: polysiloxane resin, graphene slurry, super-hydrophobic powder, dispersant, defoaming agent, organic bentonite, polyamide wax slurry, titanium white and organic solvent are sequentially added, and dispersed at high speed for 20 min under cooling condition, then ground to a fineness of less than 20 μm and filtered to obtain component A; Preparation of component B: aliphatic isocyanate is uniformly mixed and stirred with butyl acetate to obtain component B; After the components A and B are sequentially added and uniformly mixed, the coating is obtained.

[0051] Further, the water contact angle of the coating is 148°-155°, and the aging resistance is 2100-2280 h.

[0052] Example 1 The preparation method of the graphene low surface energy coating of the present embodiment comprises the following steps: 1.1 Preparation of graphene slurry Raw materials: Graphene: 100 g Dispersant: high molecular weight block copolymer containing a pigmentophilic group 100 g, binary fat 100 g Polysiloxane resin (PL2075): 400 g Organic bentonite: 50 g Butyl acetate: 250 g Operation steps: Put 100 g graphene 1233, 200 g dispersant, 400 g polysiloxane resin PL2075, 50 g organic bentonite, and 250 g butyl acetate into a dispersion kettle.

[0053] Stir at low speed in the dispersion kettle until uniformly mixed.

[0054] Increase the rotation speed of the dispersion kettle to 1200 r / min, and high-speed disperse at this speed for 20 minutes to obtain a mixture.

[0055] After high-speed dispersion is completed, transfer the mixture into a sand mill for grinding, and the fineness of grinding is required to be less than 15 μm.

[0056] After the fineness of grinding is qualified, a graphene slurry is obtained, which is stored for use.

[0057] 1.2 Preparation of component A Raw materials: Polysiloxane resin (PL2075): 480 g Graphene slurry: 100 g Polytetrafluoroethylene powder: 140 g Dispersant: 5 g of high-molecular block copolymer containing a pigmentophilic group and 5 g of dibasic fat Acrylate copolymer: 8 g Organic bentonite: 10 g Polyamide wax slurry: 20 g Titanium white powder: 100 g Butyl acetate: 50 g Propylene glycol methyl ether acetate: 32 g Xylene: 50 g Operation steps: Put 480 g of polysiloxane resin PL2075, 100 g of graphene slurry, 140 g of polytetrafluoroethylene powder, 10 g of dispersant, 8 g of acrylate copolymer, 10 g of organic bentonite, 20 g of polyamide wax slurry, 100 g of titanium white powder, 50 g of butyl acetate, 32 g of propylene glycol methyl ether acetate, and 50 g of xylene into a dispersion kettle in sequence.

[0058] Turn on the cooling water system of the dispersion kettle to prevent overheating of the reaction.

[0059] High-speed disperse at a rotation speed of 1200 r / min for 20 minutes to ensure that all components are completely and uniformly mixed to obtain a mixture A.

[0060] Transfer the dispersed mixture A into a sand mill for grinding, and the fineness of grinding is required to be less than 20 μm.

[0061] After grinding is qualified, filter and package to obtain component A.

[0062] 1.3 Preparation of low surface energy coating B component Raw materials: Aliphatic isocyanate: 768 g Butyl acetate: 232 g Operation steps: Put 768 g of aliphatic isocyanate and 232 g of butyl acetate into the dispersion kettle.

[0063] Stir evenly to ensure that the aliphatic isocyanate is completely dissolved in the butyl acetate to obtain the B component.

[0064] 1.4 Mixing of A component and B component Operation steps: Take the A component and the B component, mix them together and stir until evenly dispersed to obtain the final coating.

[0065] Example 2 The preparation method of a graphene low surface energy coating in this example includes the following steps: 1.1 Preparation of graphene slurry Raw materials: Graphene: 100 g Dispersant: high molecular weight block copolymer containing a pigmentophilic group 100 g, binary fat 100 g Silicone resin (PL2075): 400 g Organic bentonite: 50 g Butyl acetate: 250 g Operation steps: Put 100 g of graphene 1233, 200 g of dispersant, 400 g of silicone resin PL2075, 50 g of organic bentonite, and 250 g of butyl acetate into the dispersion kettle.

[0066] Stir at low speed in the dispersion kettle until evenly mixed.

[0067] Increase the rotation speed of the dispersion kettle to 1200 r / min, and disperse at high speed for 20 minutes to obtain the mixture.

[0068] After high-speed dispersion is completed, transfer the mixture into a sand mill for grinding, and the fineness of grinding is required to be less than 15 μm.

[0069] After the fineness of grinding is qualified, the graphene slurry is obtained and stored for use.

[0070] 1.2 Preparation of A component Raw materials: Silicone resin (PL2075): 500 g Graphene slurry: 100 g Polytetrafluoroethylene powder: 120 g Dispersant: high molecular block copolymer containing pigment-philic group 5 g and binary fat 5 g Acrylate copolymer: 8 g Organic bentonite: 10 g Polyamide wax paste: 20 g Titanium white powder: 100 g Butyl acetate: 50 g Propylene glycol methyl ether acetate: 32 g Xylene: 50 g Operation steps: 500 g of polysiloxane resin PL2075, 100 g of graphene paste, 120 g of polytetrafluoroethylene powder, 10 g of dispersant, 8 g of acrylate copolymer, 10 g of organic bentonite, 20 g of polyamide wax paste, 100 g of titanium white powder, 50 g of butyl acetate, 32 g of propylene glycol methyl ether acetate and 50 g of xylene are sequentially added to the dispersing kettle.

[0071] Turn on the cooling water system of the dispersing kettle to prevent overheating of the reaction.

[0072] High-speed dispersion at 1200 r / min for 20 minutes to ensure that all components are completely mixed to obtain a homogeneous mixture A.

[0073] The dispersed mixture A is transferred to a sand mill for grinding, and the grinding fineness is required to be less than 20 μm.

[0074] After grinding, filtering and packaging, the A component is obtained.

[0075] 1.3 Preparation of low surface energy coating B component Raw materials: Aliphatic isocyanate: 800 g Butyl acetate: 200 g Operation steps: 800 g of aliphatic isocyanate and 200 g of butyl acetate are added to the dispersing kettle.

[0076] Stir evenly to ensure that the aliphatic isocyanate is completely dissolved in the butyl acetate to obtain the B component.

[0077] 1.4 Mixing of A component and B component Operation steps: Take the A component and the B component, mix them and stir until evenly dispersed to obtain the final coating.

[0078] Example 3 The preparation method of a graphene low surface energy coating of this example includes the following steps: 1.1 Preparation of graphene paste Raw materials: Graphene: 100 g Dispersant: high molecular block copolymer containing pigmentophilic group 100 g, binary fat 100 g Polysilicone resin (PL2075): 400 g Organic bentonite: 50 g Butyl acetate: 250 g Operation steps: Put 100 g of graphene 1233, 200 g of dispersant, 400 g of polysilicone resin PL2075, 50 g of organic bentonite, and 250 g of butyl acetate into the dispersion kettle.

[0079] Stir at low speed in the dispersion kettle until uniformly mixed.

[0080] Increase the rotation speed of the dispersion kettle to 1200 r / min, and disperse at high speed for 20 minutes to obtain a mixture.

[0081] After high-speed dispersion is completed, the mixture is transferred into a sand mill for grinding, and the fineness of grinding is required to be less than 15 μm.

[0082] After the fineness of grinding is qualified, a graphene slurry is obtained and stored for use.

[0083] 1.2 Preparation of Group A components Raw materials: Polysilicone resin (PL2075): 520 g Graphene slurry: 100 g Polytetrafluoroethylene powder: 100 g Dispersant: high molecular block copolymer containing pigmentophilic group 5 g and binary fat 5 g Acrylate copolymer: 8 g Organic bentonite: 10 g Polyamide wax slurry: 20 g Titanium white powder: 100 g Butyl acetate: 50 g Propylene glycol methyl ether acetate: 32 g Xylene: 50 g Operation steps: Put 520 g of polysilicone resin PL2075, 100 g of graphene slurry, 100 g of polytetrafluoroethylene powder, 10 g of dispersant, 8 g of acrylate copolymer, 10 g of organic bentonite, 20 g of polyamide wax slurry, 100 g of titanium white powder, 50 g of butyl acetate, 32 g of propylene glycol methyl ether acetate, and 50 g of xylene into the dispersion kettle in sequence.

[0084] Turn on the cooling water system of the dispersion kettle to prevent overheating of the reaction.

[0085] High-speed dispersion for 20 minutes at 1200 r / min to ensure complete mixing of all components.

[0086] Grind the dispersed mixture A in a sand mill to a fineness of less than 20 μm.

[0087] After grinding, filter and package to obtain component A.

[0088] 1.3 Preparation of low surface energy coating B component Raw materials: Aliphatic isocyanate: 832 g Butyl acetate: 168 g Operation steps: Add 832 g of aliphatic isocyanate and 168 g of butyl acetate to a dispersion kettle.

[0089] Stir until the aliphatic isocyanate is completely dissolved in the butyl acetate to obtain component B.

[0090] 1.4 Mixing of component A and component B Operation steps: Take component A and component B, mix and stir until evenly dispersed to obtain the final coating.

[0091] Experimental Example 1: Performance test of the coating Verify the water contact angle, aging resistance and adhesion of the coating to ensure its superhydrophobicity and weather resistance, suitable for application in extreme environments.

[0092] 1.1 Experimental materials: Experimental group: graphene low surface energy coating prepared in Example 1, Example 2 and Example 3; Control group: Comparative Example 1, wherein the coating used in the comparative example 1 is a common coating on the market without the addition of graphene material; Comparative Example 2, wherein the resin used in the comparative example 2 is not polysiloxane resin PL2075, but hydroxyl acrylate resin.

[0093] 1.2 Experimental equipment: contact angle meter, constant temperature and humidity chamber, adhesion tester, sand mill, UV aging chamber.

[0094] 1.3 Experimental steps: 1.3.1 Coating sample preparation: Surface cleaning: select several aluminum plates as substrates, clean with cleaning agent and wipe dry to ensure that the surface is free of oil or dust.

[0095] Coating: use the coatings of the experimental group and the control group mentioned above, use spraying method to uniformly coat the coatings on the surface of the substrates.

[0096] Dry curing: Place the coated substrate at room temperature for natural drying.

[0097] 1.3.2 Water contact angle test: Drop a small amount of distilled water on each sample and use a contact angle meter to measure the water contact angle on the surface of the coating.

[0098] 1.3.3 Aging resistance test: UV aging: Place the coated sample in a UV aging chamber to simulate long-term UV radiation environment. Set the UV intensity to 0.8 W / m 2 , cycle for 12 hours of light and 12 hours of darkness per day to simulate long-term outdoor exposure.

[0099] Hygrothermal cycling: In a constant temperature and humidity chamber, set the temperature to 60°C and the humidity to 90%. Check every 500 hours and observe the changes in the coating, record whether the coating has aged, discolored or hydrophobicity decreased.

[0100] Every 500 hours, take out the sample and perform water contact angle test, record the changes.

[0101] 1.3.4 Adhesion test: Tape test: Use standard tape test method, apply tape on the surface of the coating, then quickly peel off and observe whether the coating has peeled off or adhesion decreased.

[0102] Evaluate the adhesion of the coating, respectively, 0 level: no obvious peeling; 1 level: slight peeling; 2 level: obvious peeling; 3 level: completely peeled off.

[0103] 1.3.5 Film thickness detection Measure the film thickness after the paint is sprayed and cured.

[0104] Film thickness detection method: Tools: Use digital film thickness gauge.

[0105] Detection process: Randomly select multiple locations on the surface of the coated substrate for film thickness measurement, make 5 measurements to ensure the representativeness of the measurement. Use the probe of the digital film thickness gauge to contact the surface of the coating.

[0106] Record the film thickness data at each measurement point and ensure that the measurement positions are not repeated and cover the entire coating surface.

[0107] Statistical measurement results, calculate the average value of film thickness.

[0108] 1.4 Data recording and analysis: Record the data after each experiment.

[0109] 1.5 Performance evaluation of finished product The final performance of the product is shown in Table 1 below.

[0110] Table 1 Test results

[0111] According to the data provided in Table 1 above, the graphene low surface energy coating provided by the present application has excellent water contact angle and aging resistance. By comparing the water contact angle and aging resistance test results of the coating, it can be concluded that the coating has excellent super-hydrophobicity, with a water contact angle of 148°, which is much higher than the water contact angle of ordinary coatings, which is usually less than 120°. This feature makes the coating form a strong repulsive force when in contact with water-based substances, effectively blocking the penetration of moisture, thereby improving the surface waterproof and corrosion resistance, and is suitable for fields requiring waterproof and anti-fouling, such as outdoor building coatings, ships, and automotive coatings.

[0112] The aging resistance of the coating is also a highlight of this embodiment. According to the test, the aging resistance time is 2100 hours, showing that the coating can still maintain its original performance when exposed to ultraviolet light and a humid and hot environment for a long time, without significant degradation or loss of performance. This feature enables the coating to maintain stable super-hydrophobicity and corrosion resistance during long-term use, greatly extending the service life of the coating.

[0113] From the preparation method, this embodiment effectively improves the physical properties of the coating by using a composite formulation of graphene slurry and polysiloxane resin. Graphene, as a nanoscale material, is widely used to improve the mechanical properties and wear resistance of materials due to its unique two-dimensional structure and good mechanical strength.

[0114] In summary, the graphene low surface energy coating of the present application successfully achieves excellent water contact angle, aging resistance, and good mechanical and physical properties through formulation design and scientific preparation methods. These advantages make the coating have wide application prospects in many fields, especially in special environments that require long-term weather resistance.

[0115] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make some minor changes or modifications to the above-mentioned technical content without departing from the technical solution of the present application, and the equivalent embodiments with equivalent changes can be obtained. The embodiments in the above examples can be further combined or replaced, as long as they do not deviate from the technical solution of the present application. Any simple modification, equivalent change and modification of the above examples according to the technical essence of the present application are still within the scope of the present application.

Claims

1. A graphene low surface energy coating, characterized in that, The coating comprises a component A and a component B, wherein: The component A is composed of the following raw materials in parts by mass: Polydimethylsiloxane resin 400-600 parts; Graphene slurry 80-150 parts; Super-hydrophobic powder 100-150 parts; Dispersant 5-15 parts; Defoaming agent 5-10 parts; Organic bentonite 5-15 parts; Polyamide wax slurry 10-25 parts; Titanium white powder 80-120 parts; Organic solvent 100-150 parts; The component B comprises the following raw materials in parts by mass: Aliphatic isocyanate curing agent 700-900 parts, Butyl acetate 150-250 parts.

2. The graphene low surface energy coating of claim 1, wherein, The graphene slurry comprises the following raw materials in parts by mass: graphene 80-120 parts, dispersant 150-250 parts, polydimethylsiloxane resin 300-500 parts, organic bentonite 30-60 parts, and solvent 200-300 parts.

3. The graphene low surface energy coating of claim 2, wherein, The solvent is butyl acetate.

4. The graphene low surface energy coating of claim 1, wherein, The organic solvent is a mixture of propylene glycol methyl ether acetate, butyl acetate, and dimethylbenzene.

5. The graphene low surface energy coating of claim 1, wherein, The polydimethylsiloxane resin is a hydroxyl-terminated or methyl-terminated polydimethylsiloxane resin.

6. The graphene low surface energy coating of claim 2, wherein, The dispersant is a mixture of a high-molecular block copolymer containing a pigmentophilic group and a binary fat, with a mass ratio of 1:

1.

7. The graphene low surface energy coating of claim 2, wherein, The defoaming agent is a non-silicon polymer or an acrylate copolymer.

8. The graphene low surface energy coating of claim 1, wherein, The super-hydrophobic powder is a polytetrafluoroethylene powder with a particle size of 5-10 μm.

9. A process for the preparation of a graphene low surface energy coating as claimed in any one of claims 1 to 8 characterised in that, The method comprises the following steps: Preparation of graphene slurry: graphene, dispersant, polydimethylsiloxane resin, organic bentonite, and butyl acetate are sequentially added, uniformly mixed at low speed, then dispersed at a speed of 1200 r / min for 20 min, and finally ground to a fineness of less than 15 μm to obtain the graphene slurry; Preparation of component A: polydimethylsiloxane resin, graphene slurry, super-hydrophobic powder, dispersant, defoaming agent, organic bentonite, polyamide wax slurry, titanium white powder, and organic solvent are sequentially added, and dispersed at high speed for 20 min under cooling conditions, then ground to a fineness of less than 20 μm and filtered to obtain the component A; Preparation of component B: aliphatic isocyanate is mixed with butyl acetate to obtain the component B; Mixing and application: the component A and the component B are sequentially added and uniformly mixed to obtain the coating.

10. The method of claim 9, wherein the graphene low surface energy coating is prepared by the steps of: a) providing a graphene dispersion; b) providing a polymeric binder; c) mixing the graphene dispersion and the polymeric binder; d) applying the mixture to a substrate; and e) curing the mixture. The water contact angle of the coating is 148°-155°, and the aging resistance is 2100-2280 h.

Images