Nano-graphene heat-dissipation hydrophobic coating and preparation method thereof

Abstract

The invention discloses a nano graphene heat dissipation hydrophobic coating and a preparation method thereof.The hydrophobic coating comprises a film forming component and a curing component, and the film forming component preparation method comprises the following steps that S1, a wetting agent and a dispersing agent fluorinated polyacrylate are added into a solvent propylene glycol methyl ether acetate, and stirring and ultrasonic oscillation are conducted; s2, adding silane coupling modified nano-silica particle loaded nano-graphene into the material obtained in the step S1 in batches; s3, ball milling dispersion; s4, adding hydroxyl methyl acrylate and a water repellent agent tridecafluorooctyltriethoxysilane into the material obtained in the step S3 under continuous stirring; s5, continuously adding a flatting agent polyether modified polydimethylsiloxane and a defoaming agent BYK-024 under a stirring condition, and stirring to obtain a film forming component; and S6, uniformly stirring the film-forming component and the curing component to obtain the target nano-graphene heat-dissipation hydrophobic coating. After being cured to form a film, the coating has heat conduction, hydrophobicity and mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation and hydrophobic coating technology, and in particular to a nano-graphene heat dissipation and hydrophobic coating and its preparation method. Background Technology

[0002] With the rapid development of technology, more and more miniaturized electronic products are entering people's lives, bringing with them an increasingly demanding need for efficient heat dissipation. During operation, the heat generated by electronic components increases and accumulates, and if it cannot dissipate quickly enough, some areas of the electronic device exceed the ideal operating temperature range. Prolonged operation at high temperatures can accelerate the aging of electronic components, affecting the lifespan of the device. Therefore, more effective heat dissipation methods are needed to ensure the heat dissipation efficiency of electronic devices, improve their heat generation, and extend their lifespan.

[0003] Graphene possesses excellent thermal conductivity, with single-layer graphene exhibiting a thermal conductivity as high as 5300 W / m·K, a thermal emissivity exceeding 0.9, and a large specific surface area, theoretically reaching 2630 m² / g. This makes it a high-performance and suitable additive for heat-dissipating coatings. However, the large specific surface area of ​​graphene hinders its dispersion in coatings, easily leading to agglomeration. Unevenly dispersed graphene makes it difficult to increase the heat dissipation area, widen the heat dissipation path, and achieve a high thermal conductivity. Consequently, the thermal conductivity of the resulting film is compromised, and the mechanical strength of the film is also negatively affected. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a nano-graphene heat dissipation and hydrophobic coating. This invention uses methyl hydroxyacrylate as the main film-forming substance, controls the order of addition during the preparation process, utilizes tridecafluorooctyltriethoxysilane to enrich the coating interface, and at the same time, the silane groups in PFOTES react with the hydroxyl groups of hydroxyl acrylic resin to form Si-O covalent bonds. The condensation reaction between PEG-PDMS and the siloxane groups of PFOTES forms a three-dimensional Si-O-Si network, which can effectively disperse and fix PFOTES, forming a three-dimensional network structure that takes into account both internal and external properties. After the coating is cured into a film, it has the properties of thermal conductivity, hydrophobicity and mechanical strength.

[0005] To solve this technical problem, the technical solution of the present invention is: a method for preparing a nano-graphene heat dissipation and hydrophobic coating, wherein the hydrophobic coating includes a film-forming component and a curing component, and the method for preparing the film-forming component includes the following steps: S1. Add the wetting agent and dispersant fluorinated polyacrylate to the solvent propylene glycol methyl ether acetate, stir, and ultrasonically vibrate. S2. The silane-coupled modified graphene loaded with nano-silica particles is uniformly divided and added to the material obtained in step S1 in batches. The mixture is ultrasonically vibrated and stirred until there are no obvious particles. S3, ball milling dispersion; S4. Add methyl hydroxyacrylate and hydrophobic agent tridecylfluorooctyltriethoxysilane to the material after S3 under continuous stirring. Keep stirring, and the hydroxyl groups of methyl hydroxyacrylate will condense siloxane bonds with tridecylfluorooctyltriethoxysilane. S5. Under stirring conditions, add leveling agent polyether-modified polydimethylsiloxane and defoamer BYK-024. Stir, and the polyether-modified polydimethylsiloxane and tridecafluorooctyltriethoxysilane undergo a condensation reaction to form a three-dimensional Si-O-Si network, thus obtaining the film-forming component. S6. Stir the film-forming component and the curing component evenly to obtain the target nano-graphene heat dissipation and hydrophobic coating.

[0006] The preferred film-forming components include the following substances in parts by mass: 40-60 parts of hydroxyl acrylic resin; 3-10 parts of silane-coupled modified nano-silica / nano-graphene; 3-7 parts of tridecafluorooctyltriethoxysilane; 1-5 parts wetting agent; 1-5 parts of fluorinated polyacrylate; 0.5-1.5 parts of defoamer; 0.5-1.5 parts of polyether-modified polydimethylsiloxane; 20-40 parts of propylene glycol methyl ether acetate.

[0007] The preferred curing component comprises the following substances in 100 parts by weight: Curing agent: 60-80 parts of isophorone diisocyanate; The solvent, ethyl acetate, remains in the balance.

[0008] A preferred method for preparing silane-coupled modified nano-silica / nano-graphene includes the following steps: T1. Add nano-graphene to ethanol and disperse it using ultrasound; T2. Add hydrazine hydrate, ammonia, and tetraethyl orthosilicate to the dispersion in step T1, stir until homogeneous, perform hydrothermal reaction, filter, and freeze dry to obtain nano-silica / nano-graphene. T3. Add KH-550 silane coupling agent to the ethanol aqueous solution and hydrolyze by ultrasonic oscillation; T4. Add the nano-silica / nano-graphene obtained in step T2 to the KH-550 silane coupling agent hydrolyzed in step T3, stir and react at 50°C for 8 hours, filter and dry at 60°C for 12 hours to obtain silane-coupled modified nano-silica / nano-graphene.

[0009] This invention modifies nano-graphene to obtain modified nano-graphene that balances hydrophobicity, thermal conductivity, and dispersibility. Utilizing graphene's inherent high thermal conductivity and natural water-repellent ability, a layer of hydrophobic nano-silica is grown in situ on its surface. This allows the nano-silica to complement the natural water-repellent properties of graphene, further enhancing the hydrophobicity of the modified nano-graphene. Furthermore, the amount of tetraethyl orthosilicate used during the preparation process is controlled to manage the nano-silica loading, preventing excessive nano-silica from affecting thermal conductivity. Based on this, KH-550 silane coupling agent is used to modify the surface of the silica-loaded nano-graphene, improving its dispersibility in coatings and preventing agglomeration. Through the combination of these methods, a silane-coupled modified nano-silica / nano-graphene with balanced hydrophobicity, thermal conductivity, and dispersibility is finally prepared.

[0010] In preferred step T1, the mass ratio of ethanol to nanographene is 1:(0.003-0.01). The volume ratio of hydrazine hydrate, ammonia, and tetraethyl orthosilicate in step T2 to ethanol in step T1 is (0.005-0.02):(0.02-0.06):(0.01-0.05):1; The process conditions for the hydrothermal reaction in step T3 are: 160-200 ℃, hydrothermal reaction for 10-16 h; In step T4, the ethanol-water solution has a volume ratio of ethanol to water of 19:1. The volume ratio of the ethanol aqueous solution to KH-550 silane coupling agent is (20-60):1; Based on KH-550 silane coupling agent, the amount of silica-supported graphene nanoparticles added is 2-5 g / ml.

[0011] The preferred process parameters for uniform mixing in step S1 are as follows: After stirring at 600-1000 rpm for 10-20 min, ultrasonically vibrate for 5-15 min.

[0012] In preferred step S2, the mixture is continuously stirred at 600-1000 rpm, and methyl hydroxyacrylate and a hydrophobic agent are added. After stirring at 800-1200 rpm for 5-15 minutes, a leveling agent and a defoamer are added. Finally, the mixture is stirred at 800-1200 rpm for 40-60 minutes to obtain the film-forming component.

[0013] The preferred mass ratio of film-forming component to curing component is (4-10):1.

[0014] Another objective of this invention is to provide a nano-graphene heat dissipation and hydrophobic coating with a hydrophobic surface and a three-dimensional network structure formed within the coating, which combines hydrophobicity, heat dissipation, and mechanical strength.

[0015] By adopting the above technical solution, the beneficial effects of the present invention are: This invention adds tridecafluorooctyltriethoxysilane (PFOTES) as a key hydrophobic component to hydrophobic coatings, effectively compensating for the slightly weak hydrophobicity of modified nano-graphene. Due to the low surface energy of the fluorinated segments / groups, they self-accumulate and migrate to the coating surface, forming a hydrophobic barrier composed of fluorinated segments / groups. Simultaneously, the silane groups in PFOTES react with the hydroxyl groups of hydroxyl acrylic resin to form Si-O covalent bonds, firmly fixing them to the hydroxyl acrylic resin. Furthermore, fluorinated polyacrylate (PFEMA) and hydroxyl acrylic resin, both belonging to the acrylic class, have good compatibility. PFEMA can be uniformly distributed in the matrix, and its fluorinated segments can impart a certain degree of hydrophobicity to the internal matrix, resulting in good hydrophobicity both inside and outside the coating. In addition, a reaction occurs between polyether-modified polydimethylsiloxane (PEG-PDMS) and the silane groups of PFOTES, such as R1-Si-OH + R2-Si-OH → R1-Si-O-Si-R2 + The condensation reaction of H2O forms a three-dimensional Si-O-Si network, which can effectively disperse and fix PFOTES, forming a three-dimensional hydrophobic network that is both internal and external. The addition of silane-coupled modified nano-silica / nano-graphene reacts with siloxane-containing substances in the coating to form Si-O / Si-N bonds, which, combined with hydrogen bonding, makes the modified nano-graphene more uniformly dispersed and participates in the construction of the hydrophobic network through physical water repellency.

[0016] This invention, based on the aforementioned material composition, also requires control over the specific preparation process. First, fluorinated polyacrylate (PFEMA) is added as a dispersant. Then, silane-coupled modified nano-silica / nano-graphene is added to ensure the basic dispersibility of the modified nano-graphene in the coating. Subsequently, a circulating ball milling method is used to further break down any possible micro-agglomerates of the modified nano-graphene in the system, achieving optimal dispersion and allowing the modified nano-graphene to exert its proper hydrophobic and thermal conductivity. Furthermore, the order in which the matrix (hydroxyl acrylic resin), hydrophobic agent, leveling agent, and defoamer are added during the preparation process is controlled. This allows the matrix to react with the hydrophobic agent first, followed by the formation of the finished coating under the action of the leveling agent and defoamer. The cured coating film combines hydrophobicity, heat dissipation performance, and mechanical strength. Attached Figure Description

[0017] Figure 1 These are contact angle photographs of the coatings obtained in Example 3 and the blank group of the present invention.

[0018] in Figure 1 a is a photograph of the contact angle of the coating prepared in Example 3 of this invention after application. Figure 1 b is the contact angle photo of the blank group. Detailed Implementation

[0019] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0020] Example 1 This embodiment discloses a method for preparing a nano-graphene heat-dissipating and hydrophobic coating. The coating comprises a film-forming component and a curing component, wherein the preparation method of the film-forming component includes the following steps: S1. Add the wetting agent and dispersant fluorinated polyacrylate to the solvent propylene glycol methyl ether acetate, stir at 800 rpm for 20 min, and then sonicate for 10 min. S2. Divide the silane-coupled modified graphene loaded with nano-silica particles into 10 equal parts. Add the silane-coupled modified graphene loaded with nano-silica particles to the mixture obtained in step S1 every 30 seconds. After ultrasonic oscillation for 20 minutes, stir and disperse at 2000 rpm for 60 minutes until there are no obvious particles. S3. Ball milling and dispersion 3 times, with the following process parameters each time: 320 rpm / min, 10 minutes each time; S4. The mixture of materials after S3 is continuously stirred at 800 rpm. While stirring, methyl hydroxyacrylate and hydrophobic agent tridecafluorooctyltriethoxysilane are added. Stirring is maintained. The hydroxyl groups of methyl hydroxyacrylate and tridecafluorooctyltriethoxysilane condense siloxane bonds. S5. After stirring at 1000 rpm for 10 min, add leveling agent polyether-modified polydimethylsiloxane and defoamer BYK-024. Stir at 1000 rpm for 60 min. The polyether-modified polydimethylsiloxane and the siloxane groups of tridecafluorooctyltriethoxysilane undergo a condensation reaction to form a three-dimensional Si-O-Si network, thus obtaining the film-forming component. S6. Stir the film-forming component and the curing component at a mass ratio of 6:1 at 1200 rpm for 40 min to obtain the target nano-graphene heat dissipation and hydrophobic coating.

[0021] In this embodiment, the film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts; Three parts of silane-coupled modified nano-silica particles / nano-graphene; 3 parts of hydrophobic agent tridecafluorooctyltriethoxysilane; Evonik TEGO Wet 2801.5 parts; Dispersant: 1.5 parts fluorinated polyacrylate; 0.5 parts of defoamer BYK-024 (by BYK Chemicals); Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane; Solvent: 40 parts propylene glycol methyl ether acetate; The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate; Solvent: ethyl acetate 25 parts; Isophorone diisocyanate was slowly added to the solvent ethyl acetate and stirred at 800 rpm for 20 min to obtain the cured component. The preparation method of silane coupling modified nano-silica / nano-graphene in this embodiment includes the following steps: T1. Add nano-graphene to ethanol at a mass ratio of 1:0.005, and then disperse it ultrasonically for 1 h. T2. Add hydrazine hydrate, ammonia, and tetraethyl orthosilicate to the dispersion in step T1, stir until homogeneous, perform hydrothermal reaction, filter, and freeze dry to obtain nano-silica / nano-graphene. Hydrazine hydrate, ammonia, and tetraethyl orthosilicate were added to the dispersion in step T1 at a volume ratio of 0.01:0.04:0.02:1 to ethanol in step T1. The mixture was stirred at 400 rpm for 30 min, then hydrothermally heated at 180 °C for 12 h, filtered, and freeze-dried for 24 h to obtain nano-silica / nano-graphene.

[0022] T3. Add KH-550 silane coupling agent to the ethanol-water solution at a volume ratio of 50:1 and hydrolyze by ultrasonic vibration for 30 min; in step T4, the volume ratio of ethanol to water in the ethanol-water solution is 19:1. T4. Add the nano-silica / nano-graphene obtained in step T2 to the KH-550 silane coupling agent hydrolyzed in step T3, stir and react at 50°C for 8 hours, filter and dry at 60°C for 12 hours to obtain silane-coupled modified nano-silica / nano-graphene.

[0023] The mass ratio of nano-silica / nano-graphene to the volume ratio of KH-550 silane coupling agent is 3g:1ml.

[0024] Example 2 This embodiment discloses a nano-graphene heat dissipation and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts; Five parts of silane-coupled modified nano-silica particles / nano-graphene; Three parts of hydrophobic agent tridecafluorooctyltriethoxysilane; Evonik TEGO Wet 2801.5 parts; Dispersant: 1.5 parts fluorinated polyacrylate 0.5 parts of defoamer BYK-024 (by BYK Chemicals); Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane; Solvent: 40 parts of propylene glycol methyl ether acetate; The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent The preparation methods of the nano-graphene heat dissipation and hydrophobic coating and the preparation methods of silane coupling modified nano-silica particles / nano-graphene in this embodiment are the same as those in Example 1.

[0025] Example 3 This embodiment discloses a nano-graphene heat dissipation and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts; 7 parts of silane-coupled modified nano-silica particles / nano-graphene; Three parts of hydrophobic agent tridecafluorooctyltriethoxysilane; Evonik TEGO Wet 2801.5 parts; Dispersant: 1.5 parts fluorinated polyacrylate; 0.5 parts of defoamer BYK-024 (by BYK Chemicals); Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane; Solvent: 40 parts of propylene glycol methyl ether acetate; The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent The preparation methods of the nano-graphene heat dissipation and hydrophobic coating and the preparation methods of silane coupling modified nano-silica particles / nano-graphene in this embodiment are the same as those in Example 1.

[0026] Comparative Example 1 This comparative example discloses a nano-graphene heat-dissipating and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts 7 portions of nano-graphene Bailingwei graphene micro flakes 3 parts of hydrophobic agent tridecafluorooctyltriethoxysilane Evonik TEGO Wet 2801.5 parts Dispersant: 1.5 parts fluorinated polyacrylate 0.5 parts of defoamer (BYK-024) from BYK Chemicals Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane Solvent: 40 parts of propylene glycol methyl ether acetate The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent The preparation method of the nano-graphene heat dissipation and hydrophobic coating in this comparative example is the same as that in Example 1.

[0027] Comparative Example 2 This comparative example discloses a nano-graphene heat-dissipating and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts; 7 parts of silane-coupled modified nano-silica particles / nano-graphene; Three parts of hydrophobic agent tridecafluorooctyltriethoxysilane; Evonik TEGO Wet 2801.5 parts; Dispersant: 1.5 parts fluorinated polyacrylate; 0.5 parts of defoamer BYK-024 (by BYK Chemicals); Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane; Solvent: 40 parts of propylene glycol methyl ether acetate; The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent The preparation method of the silane coupling modified nano-silica particles / nano-graphene in this comparative example is the same as that in Example 1.

[0028] The difference between the preparation method of the nano-graphene heat dissipation and hydrophobic coating in this comparative example and the example is that the step of cyclic ball milling in step S12 is omitted in this comparative example.

[0029] Comparative Example 3 This comparative example discloses a nano-graphene heat-dissipating and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts 7 parts of silane-coupled modified nano-silica particles / nano-graphene Evonik TEGO Wet 2801.5 parts Dispersant: 1.5 parts fluorinated polyacrylate 0.5 parts of defoamer (BYK-024) from BYK Chemicals Leveling agent: 0.5 parts of polyether-modified polydimethylsiloxane Solvent: 40 parts of propylene glycol methyl ether acetate The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent In this comparative example, the preparation methods of the nano-graphene heat dissipation and hydrophobic coating and the preparation methods of silane coupling modified nano-silica particles / nano-graphene are the same as those in Example 1.

[0030] Comparative Example 4 This comparative example discloses a nano-graphene heat-dissipating and hydrophobic coating, which includes a film-forming component and a curing component by weight: The film-forming component includes the following components: Components: Specifications: Dosage: Hydroxyacrylate resin, Setalux 27-13, 1660 parts 7 parts of silane-coupled modified nano-silica particles / nano-graphene 3 parts of hydrophobic agent tridecafluorooctyltriethoxysilane Evonik TEGO Wet 2801.5 parts Dispersant: 1.5 parts fluorinated polyacrylate 0.5 parts of defoamer (BYK-024) from BYK Chemicals Leveling agent: MFP T 0.5 parts Solvent: 40 parts of propylene glycol methyl ether acetate The curing component includes the following components: Components: Specifications: Dosage: Curing agent: 75 parts isophorone diisocyanate 25 parts of ethyl acetate solvent In this comparative example, the preparation methods of the nano-graphene heat dissipation and hydrophobic coating and the preparation methods of silane coupling modified nano-silica particles / nano-graphene are the same as those in Example 1.

[0031] The coatings prepared in Examples 1-3 and Comparative Examples 1-4 were applied to the surface of 100 mm × 50 mm × 2 mm aluminum plates to test the heat dissipation effect of the graphene heat dissipation and hydrophobic coatings. The aluminum plates coated with the graphene heat dissipation and hydrophobic coatings and the blank aluminum plates were placed on a ceramic constant-temperature heating stage. After heating to the same temperature, the heating was stopped, and the surface temperature of the aluminum plates was measured every 2 minutes using an infrared thermometer. The test results are shown in Table 1.

[0032] Table 1. Heat dissipation effect of the films obtained in Examples 1 to 3 and Comparative Examples 1 to 4

[0033] The heat dissipation and hydrophobic coatings prepared in Examples 1-3 and Comparative Examples 1-4 were stirred evenly and applied to the surface of a glass plate with dimensions of 75 mm × 25 mm × 1 mm. Their hydrophobicity and water resistance were then tested, and the specific test results are shown in Table 2.

[0034] Hardness was tested according to GB / T 6739-2022 "Determination of Hardness of Paint Film by Pencil Method".

[0035] Impact resistance was tested in accordance with GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film".

[0036] Hydrophobicity was tested in accordance with GB / T 30693-2014 "Measurement of the contact angle between plastic film and water".

[0037] Water resistance was tested according to GB / T 1733-1993 "Test Method for Water Resistance of Paint Film". The coating was applied to the surface of a 120 mm × 25 mm × (0.2-0.3) mm tinplate and tested using Method A (168 h) after drying.

[0038] Table 2 Performance indicators of the coatings obtained in Examples 1 to 3 and Comparative Examples 1 to 4

[0039] According to the heat dissipation data in Table 1, the nano-graphene heat-dissipating hydrophobic coating prepared in this invention has a better heat dissipation effect compared to the blank aluminum plate, which has a poor heat dissipation effect. The coating with added nano-graphene powder exhibits good heat dissipation performance; in Example 3, the temperature dropped to room temperature in approximately 10 minutes. Comparing Example 3 and Comparative Example 1, it can be seen that the addition of nano-graphene can effectively improve the heat dissipation performance of the coating. Comparing Example 3 and Comparative Example 2, it can be seen that the coating after high-speed stirring and circulating ball milling has better uniformity and fineness, thus resulting in a better heat dissipation effect. Comparing Example 3 and Comparative Example 3, it can be seen that the hydrophobic agent added in this invention has a certain impact on the final heat dissipation performance. Comparing Example 3 and Comparative Example 4, it can be seen that the leveling agent added in this invention has a certain impact on the heat dissipation effect of the coating.

[0040] Table 2 shows that the nano-graphene heat dissipation and hydrophobic coating of the present invention has better hydrophobicity, hardness, and impact resistance. The data shows that the hydrophobic angle of the blank group was only 61.3°, while that of Example 3 reached 122.5°. Example 3 had a hardness of 2H and an impact resistance of 57 cm, while Comparative Example 1 had a hardness of H and an impact resistance of 42 cm, showing a significant improvement. Comparing Example 3 and Comparative Example 1 reveals that modifying the nano-graphene significantly improves the hydrophobicity, hardness, and impact resistance of the coating. This is because the compatibility between the nano-graphene and the coating is better after surface loading and silane modification. The modified nano-graphene can be uniformly dispersed in the coating, forming a uniform modified nano-graphene hydrophobic and thermally conductive layer, and helping to form a hydrophobic network to improve hydrophobicity, hardness, and impact resistance. Comparing Example 3 and Comparative Example 2, it can be found that the coating after high-speed stirring and circulating ball milling has a smoother surface quality, which helps the self-enrichment of fluorine-containing segments in the hydrophobic agent and helps the construction of the three-dimensional silica-silicon network, reducing the hydrophobic angle from 122.5° to 103.8° and the impact resistance from 57 cm to 48 cm. Comparing Example 3 and Comparative Example 3, it can be found that without the addition of hydrophobic agent, the coating still has a certain hydrophobicity by relying on modified nano-graphene, but the effect is poor; and the coating cannot form a hydrophobic network well, resulting in a decrease in both hydrophobicity and impact resistance. Comparing Example 3 and Comparative Example 4, it can be found that by replacing the leveling agent that does not participate in the construction of the silica-silicon network, the hydrophobic angle of the coating decreased to 114.2°, the hardness decreased to H grade, and the impact resistance decreased to 53 cm, indicating that polyether-modified polydimethylsiloxane has a good performance-enhancing effect in the construction of the silica-silicon three-dimensional network.

[0041] As can be seen from the performance tests of the examples and comparative examples, the nano-graphene powder heat dissipation and hydrophobic coating prepared by the present invention has better heat dissipation effect, hydrophobic effect, hardness and impact resistance.

Claims

1. A method for preparing a nano-graphene heat-dissipating and hydrophobic coating, characterized in that: Hydrophobic coatings include film-forming components and curing components, wherein the preparation method of the film-forming components includes the following steps: S1. Add the wetting agent and dispersant fluorinated polyacrylate to the solvent propylene glycol methyl ether acetate, stir, and ultrasonically vibrate. S2. The silane-coupled modified graphene loaded with nano-silica particles is uniformly divided and added to the material obtained in step S1 in batches. The mixture is ultrasonically vibrated and stirred until there are no obvious particles. S3, ball milling dispersion; S4. Add methyl hydroxyacrylate and hydrophobic agent tridecylfluorooctyltriethoxysilane to the material after S3 under continuous stirring. Keep stirring, and the hydroxyl groups of methyl hydroxyacrylate will condense siloxane bonds with tridecylfluorooctyltriethoxysilane. S5. Under stirring conditions, add leveling agent polyether-modified polydimethylsiloxane and defoamer BYK-024. Stir, and the polyether-modified polydimethylsiloxane and tridecafluorooctyltriethoxysilane undergo a condensation reaction to form a three-dimensional Si-O-Si network, thus obtaining the film-forming component. S6. Stir the film-forming component and the curing component evenly to obtain the target nano-graphene heat dissipation and hydrophobic coating.

2. The preparation method according to claim 1, characterized in that: The film-forming components include the following substances in parts by mass: 40-60 parts of hydroxyl acrylic resin; 3-10 parts of silane-coupled modified nano-silica / nano-graphene; 3-7 parts of tridecafluorooctyltriethoxysilane; 1-5 parts wetting agent; 1-5 parts of fluorinated polyacrylate; 0.5-1.5 parts of defoamer; 0.5-1.5 parts of polyether-modified polydimethylsiloxane; 20-40 parts of propylene glycol methyl ether acetate.

3. The preparation method according to claim 1, characterized in that: The curing component comprises the following substances in 100 parts by weight: Curing agent: 60-80 parts of isophorone diisocyanate; The solvent, ethyl acetate, remains in the balance.

4. The preparation method according to claim 1, characterized in that: A method for preparing silane-coupled modified nano-silica / nano-graphene includes the following steps: T1. Add nano-graphene to ethanol and disperse it using ultrasound; T2. Add hydrazine hydrate, ammonia, and tetraethyl orthosilicate to the dispersion in step T1, stir until homogeneous, perform hydrothermal reaction, filter, and freeze dry to obtain nano-silica / nano-graphene. T3. Add KH-550 silane coupling agent to the ethanol aqueous solution and hydrolyze by ultrasonic oscillation; T4. Add the nano-silica / nano-graphene obtained in step T2 to the KH-550 silane coupling agent hydrolyzed in step T3, stir and react at 50°C for 8 hours, filter and dry at 60°C for 12 hours to obtain silane-coupled modified nano-silica / nano-graphene.

5. The preparation method according to claim 4, characterized in that: In step T1, the mass ratio of ethanol to nanographene is 1:(0.003-0.01). The volume ratio of hydrazine hydrate, ammonia, and tetraethyl orthosilicate in step T2 to ethanol in step T1 is (0.005-0.02):(0.02-0.06):(0.01-0.05):1; The process conditions for the hydrothermal reaction in step T3 are: 160-200 ℃, hydrothermal reaction for 10-16 h; In step T4, the ethanol-water solution has a volume ratio of ethanol to water of 19:

1. The volume ratio of the ethanol aqueous solution to KH-550 silane coupling agent is (20-60):1; Based on KH-550 silane coupling agent, the amount of silica-supported graphene nanoparticles added is 2-5 g / ml.

6. The preparation method according to claim 1, characterized in that: The process parameters for achieving uniform mixing in step S1 are as follows: After stirring at 600-1000 rpm for 10-20 min, ultrasonically vibrate for 5-15 min.

7. The preparation method according to claim 1, characterized in that: In step S2, the mixture is continuously stirred at 600-1000 rpm, and methyl hydroxyacrylate and hydrophobic agent are added. After stirring at 800-1200 rpm for 5-15 min, leveling agent and defoamer are added. Finally, the mixture is stirred at 800-1200 rpm for 40-60 min to obtain the film-forming component.

8. The preparation method according to claim 1, characterized in that: The mass ratio of the film-forming component to the curing component is (4-10):

1.

9. A nano-graphene hydrophobic heat dissipation coating prepared by the preparation method according to any one of claims 1 to 8.

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