Graphene heat dissipation coating with phase change heat storage function

Abstract

The invention relates to the technical field of coatings, and particularly discloses a graphene heat dissipation coating with a phase change heat storage function. The graphene heat dissipation coating is prepared from the following components in parts by weight: 400 to 410 parts of styrene-acrylic emulsion, 100 to 110 parts of deionized water, 33 to 35 parts of an auxiliary agent, 55 to 70 parts of polyethylene glycol, 80 to 90 parts of filler, 30 to 35 parts of phase change microcapsules and 6.5 to 7.5 parts of self-dispersion graphene. The coating formed by the graphene heat dissipation coating can efficiently absorb heat through the phase change energy storage effect, and meanwhile, heat exchange with air is easier, so that the temperature rise of an electronic device can be effectively inhibited, and the stable operation of the electronic device can be maintained.

Description

Technical Field

[0001] The present application relates to the field of coating technology, and more specifically, to a graphene heat dissipation coating with phase change heat storage function. Background Art

[0002] Currently, various high-end instruments and equipment are developing towards miniaturization, lightweighting, compactness, and high efficiency. The development of ultra-large-scale integrated circuits has made the high power density characteristics of electronic devices increasingly prominent. The large amount of heat generated by high-power electronic devices will directly affect the operating stability and complete reliability of electronic devices. According to estimates, the lifespan of electronic equipment will be reduced by half for every 10°C increase in temperature. In this case, the cooling effect achieved by traditional cooling methods is limited. For example, the heat dissipation limit of air cooling systems is only 40W / cm 2 To further increase heat dissipation, the heat dissipation space must be expanded, which is inconsistent with the current trend of miniaturization, downsizing, and precision of electronic devices. In the fields of energy, automobiles, air conditioning, agriculture, chemicals, heating, aerospace, microelectronics, and information technology, there is still a demand for high-efficiency heat dissipation.

[0003] Heat dissipation paint is a specialty coating that improves the heat dissipation efficiency of surfaces and helps quickly reduce the temperature of objects. Typical heat dissipation paints are made with a polymer as a base material, to which fillers and additives with a certain degree of thermal conductivity are added. Related art includes a carbon nanotube radiant heat dissipation paint, which is prepared as follows: carbon nanotubes and aqueous dispersant UT3501 are weighed in proportion to form a mixed aqueous solution with a carbon nanotube content of 3.0% and a solid content of 5.0%. A small amount of BYK wetting agent is added and the solution is soaked for 12 hours. The solution is then ground in a sand mill for 30-60 minutes to form a uniform carbon nanotube dispersion. The carbon nanotube dispersion is then mixed with a water-based polyurethane resin to produce the heat dissipation paint. After baking to form a film, the paint produces a heat dissipation coating with a carbon nanotube content of 10%.

[0004] Regarding the aforementioned related technologies, the inventors believe that while the coatings described in these technologies can form a coating with a certain heat dissipation effect, the limited thermal conductivity of air makes heat exchange difficult between the coating and air. Even if thermally conductive fillers can achieve more uniform heat distribution on the surface of electronic devices, they are unlikely to effectively suppress temperature increases in these devices. Summary of the Invention

[0005] In related technologies, the limited thermal conductivity of air makes it difficult to exchange heat between the coating and the air, making it difficult to effectively suppress the temperature rise of electronic devices. To improve this defect, the present application provides a graphene heat dissipation coating with phase change heat storage function.

[0006] This application provides a graphene heat dissipation coating with phase change heat storage function, which adopts the following technical solution: A graphene heat dissipation coating with a phase change heat storage function, comprising the following components in parts by weight: 400-410 parts of styrene-acrylic emulsion, 100-110 parts of deionized water, 33-35 parts of an additive, 55-70 parts of polyethylene glycol, 80-90 parts of a filler, 30-35 parts of phase change microcapsules, and 6.5-7.5 parts of self-dispersed graphene; the additives include a defoamer, a viscosity regulator, a film-forming aid, and a dispersant; the filler includes carbon black; and the capsule wall components of the phase change microcapsules include melamine resin and nano-iron oxide.

[0007] By adopting the above-mentioned technical solution, this application uses a styrene-acrylic emulsion as the coating matrix, and adds phase-change microcapsules, polyethylene glycol, and self-dispersing graphene. The phase-change microcapsules can be dispersed in the coating in the form of microparticles, while the polyethylene glycol is dispersed in the coating in the form of macromolecular segments. Both the phase-change microcapsules and polyethylene glycol have phase-change energy storage properties, which can suppress the rise in coating temperature through phase-change heat absorption. Polyethylene glycol can fill the gaps between the phase-change microcapsules, allowing the phase-change material to be evenly dispersed throughout the coating, facilitating heat absorption by the phase-change material components. The self-dispersing graphene and carbon black synergistically promote heat conduction, efficiently transferring heat from the coating to the phase-change microcapsules and polyethylene glycol. The capsule walls of the phase-change microcapsules contain nano-iron oxide, which has a thermal conductivity far higher than that of melamine resin, overcoming the poor thermal conductivity of melamine resin. With the assistance of the self-dispersing graphene and carbon black, heat can be quickly transferred to the phase-change microcapsules. Furthermore, carbon black synergistically enhances the coating's radiative heat dissipation with self-dispersing graphene, enhancing heat exchange between the coating and the air. The coating formed by the graphene heat dissipation coating in this application efficiently absorbs heat through phase change energy storage, while also facilitating heat exchange with the air. This effectively suppresses temperature increases in electronic devices, helping to maintain their stable operation.

[0008] Preferably, the self-dispersed graphene is prepared according to the following method: (1) adding graphene oxide to deionized water and performing ultrasonic dispersion to obtain a graphene dispersion, adding a CTAB aqueous solution to the graphene dispersion and heating the mixture to react, thereby obtaining CTAB-modified graphene oxide; (2) CTAB-modified graphene oxide is dispersed in an organic solvent, a Grignard reagent is added, and condensation reflux is performed under heating conditions in a water bath while continuously stirring. After the reaction is completed, the product is filtered, and the product is washed and dried to obtain self-dispersed graphene.

[0009] By adopting the above technical solution, the present application first modifies graphene oxide with CTAB, and then reduces the CTAB-modified graphene oxide with a Grignard reagent. After the reduction is completed, the residues of the Grignard reagent and the CTAB residues will bind to the edges of the reduced graphene oxide. These two residues can synergistically produce a steric hindrance effect, hindering the agglomeration of the reduced graphene oxide, thereby obtaining self-dispersed graphene.

[0010] Preferably, the styrene-acrylic emulsion is prepared as follows: (1) preparing an emulsifier solution, an initiator solution, and a monomer mixture for standby use; in this step, the monomers used to prepare the monomer mixture include acrylic acid, styrene, butyl acrylate, and isooctyl acrylate; (2) adding a portion of the monomer mixture to the emulsifier solution, stirring and emulsifying, then adding a portion of the initiator solution under heating conditions in a water bath, and continuing the heat-keeping reaction to obtain an intermediate dispersion; (3) Add the remaining monomer mixture and initiator solution to the intermediate dispersion, continue to keep the temperature to react, cool down after the reaction is completed, add ammonia water to adjust the pH, and obtain a styrene-acrylic emulsion after discharging.

[0011] By adopting the above technical solution, the present application prepares a styrene acrylic emulsion using acrylic acid, styrene, butyl acrylate and isooctyl acrylate as monomers. Compared with conventional ordinary polyvinyl alcohol coatings, the coating formed by the styrene acrylic emulsion has better performance in terms of weather resistance and adhesion, and is moderately priced, has a simple preparation process, and is suitable for large-scale production.

[0012] Preferably, in the method for preparing the styrene acrylic emulsion, the monomers used to prepare the monomer mixture further include lignin-based acrylate.

[0013] By adopting the above technical solution, the lignin groups introduced by lignin-based acrylate can form hydrogen bonds with polyethylene glycol. The hydrogen bonds can enhance the interchain coupling to form a continuous thermal network, thereby providing a richer heat transfer pathway, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0014] Preferably, the lignin-based acrylate is prepared according to the following method: Alkali lignin, methylimidazole and methacrylic anhydride are mixed, stirred for reaction, and the product is added into hexane. The precipitate is collected, and the precipitate is dissolved in dichloromethane. The precipitate is washed with deionized water, and then precipitated again with hexane. The obtained precipitate is dried to obtain lignin-based acrylate.

[0015] By adopting the above technical solution, the present application uses methacrylic anhydride to react with alkali lignin to obtain lignin-based acrylate that can participate in copolymerization, thereby achieving the introduction of lignin groups.

[0016] Preferably, the auxiliary agent further comprises hydroxyethyl cellulose.

[0017] By adopting the above technical solution, hydroxyethyl cellulose can increase the hydrogen bond density inside the coating, providing more abundant heat transfer pathways, so that heat can be efficiently transferred to phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0018] Preferably, the components of the graphene heat dissipation coating further include nano-lignin.

[0019] By adopting the above technical solution, the oxygen-containing groups in the nano-lignin can effectively increase the hydrogen bond density inside the coating, and the lignin-based acrylate makes the nano-lignin and styrene acrylic emulsion have good compatibility, which promotes the uniform dispersion of the nano-lignin, thereby providing a richer heat transfer pathway, allowing heat to be efficiently transferred to the phase change microcapsules and polyethylene glycol, helping to improve the coating's effect in suppressing temperature rise.

[0020] Preferably, the components of the graphene heat dissipation coating further include hydrolyzed gelatin.

[0021] By adopting the above technical solution, the amino and carboxyl groups in the hydrolyzed gelatin can increase the hydrogen bond density inside the coating, providing more abundant heat transfer pathways, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0022] Preferably, the phase change microcapsules are prepared according to the following method: (1) Melamine, formaldehyde, nano-iron oxide and deionized water are mixed, preheated and triethanolamine is added to adjust the pH, and then the mixture is kept warm for reaction to obtain MF prepolymer for later use; SMA, emulsifier, sodium hydroxide, butyl stearate and n-tetradecanol are added to deionized water and stirred to obtain core material emulsion for later use; (2) Adding citric acid to the core material emulsion to adjust the pH, adding MF prepolymer to the core material emulsion after preheating, and obtaining a microcapsule suspension after heat preservation reaction. The microcapsule suspension is filtered, washed and dried to obtain phase change microcapsules.

[0023] By adopting the above technical solution, the present application uses a mixture of n-tetradecanol and butyl stearate as the main phase change material in the capsule core, and uses a composite of melamine resin and nano-iron oxide as the capsule wall to obtain phase change microcapsules that can efficiently absorb surrounding heat.

[0024] Preferably, in step (1) of preparing the phase-change microcapsules, hydrophobic nano-silica sol is also added when preparing the core material emulsion.

[0025] By adopting the above technical solution, the nano-silica particles in the hydrophobic nano-silica sol have good compatibility with the tetradecanol and butyl stearate in the capsule core. The nano-silica particles can enhance the thermal conductivity of the capsule core, making it easier for heat to diffuse in the capsule core, thereby improving the heat absorption efficiency of the phase change microcapsules and helping to improve the coating's effect of suppressing temperature rise.

[0026] In summary, this application has the following beneficial effects: 1. The coating formed by the graphene heat dissipation coating of the present application can efficiently absorb heat through phase change energy storage, and is also easier to exchange heat with the air, thereby effectively suppressing the temperature rise of electronic devices and helping to maintain the stable operation of electronic devices.

[0027] 2. This application first modifies graphene oxide with CTAB and then reduces the CTAB-modified graphene oxide with a Grignard reagent. After reduction, the Grignard reagent residues and CTAB residues bind to the edges of the reduced graphene oxide. These two residues synergistically produce a steric hindrance effect, hindering the aggregation of the reduced graphene oxide and achieving self-dispersion of the graphene.

[0028] 3. This application improves the thermal conductivity of phase change microcapsules through nano-iron oxide and hydrophobic nano-silica sol, making it easier for heat to diffuse in the capsule core, improving the heat absorption efficiency of the phase change microcapsules, and helping to improve the coating's effect of suppressing temperature rise. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0030] Preparation example of self-dispersed graphene The following is an explanation using Preparation Example 1.

[0031] Preparation Example 1 In this preparation example, self-dispersed graphene was prepared according to the following method: (1) 1 g of graphene oxide was added to 100 mL of deionized water and ultrasonically dispersed for 1 h to obtain a graphene dispersion. 11 mL of a 1 wt% CTAB aqueous solution was added to the graphene dispersion and the temperature was raised to 90° C. The mixture was heated and stirred for 4 h to obtain CTAB-modified graphene oxide. (2) CTAB-modified graphene oxide, tetrahydrofuran, and thienylmagnesium bromide were weighed in a ratio of 5 g:30 mL:10 g, CTAB-modified graphene oxide was added to tetrahydrofuran for dispersion, thienylmagnesium bromide was added, and the mixture was condensed and refluxed in a water bath at 80 ° C for 24 h with continuous stirring. After the reaction was completed, the mixture was filtered, and the product was washed with tetrahydrofuran, deionized water, and hydrochloric acid in sequence, and then vacuum-dried at 60 ° C to obtain self-dispersed graphene.

[0032] Preparation example of styrene acrylic emulsion The following is an illustration of Preparation Example 2.

[0033] Preparation Example 2 In this preparation example, styrene acrylic emulsion was prepared according to the following method: (1) 20 g of sodium dodecyl diphenyl ether disulfonate and 96.6 g of deionized water were mixed and stirred to dissolve to obtain an emulsifier solution, which was set aside; 0.3 g of ammonium persulfate, 0.25 g of sodium bicarbonate and 30 g of deionized water were mixed to obtain an initiator solution, which was set aside; 1 g of acrylic acid, 44.4 g of styrene, 27.8 g of butyl acrylate and 27.8 g of isooctyl acrylate were mixed to obtain a monomer mixture, which was set aside; (2) adding 1 / 10 weight of the monomer mixture to the emulsifier solution, stirring and emulsifying, and then adding 1 / 3 weight of the initiator solution under heating conditions at 85°C in a water bath, and continuing the reaction at this temperature for 15 minutes to obtain an intermediate dispersion; (3) Add the remaining monomer mixture and initiator solution to the intermediate dispersion over a period of 5 hours, continue to keep the temperature for reaction for 1 hour, cool down after the reaction is completed, add ammonia water to adjust the pH, and obtain styrene-acrylic emulsion after discharging.

[0034] Preparation Example 3 The difference between this preparation example and Preparation Example 2 is that, in the method for preparing the styrene-acrylic emulsion, the monomers used to prepare the monomer mixture further include 10 g of lignin-based acrylate, which is prepared as follows: 10 g of alkali lignin, 20 mL of methylimidazole, and methacrylic anhydride having a molar concentration of hydroxyl groups equivalent to 80 times that of the alkali lignin were mixed and stirred for reaction for 2.5 hours. The product was then added to 1 L of hexane, and the precipitate was collected and dissolved in 100 mL of dichloromethane. The precipitate was washed with deionized water and then precipitated again with 1 L of hexane. The resulting precipitate was dried to obtain lignin-based acrylate.

[0035] Preparation example of phase change microcapsules The following is an illustration of Preparation Example 4.

[0036] Preparation Example 4 In this preparation example, phase change microcapsules were prepared according to the following method: (1) 3 g of melamine, 14 g of a 37 wt% formaldehyde solution, 0.15 g of nano-iron oxide, and 14 g of deionized water were mixed, preheated at 75° C., triethanolamine was added to adjust the pH to 8.5, and then the mixture was kept warm for 30 min to obtain an MF prepolymer for later use; 2 g of SMA, 1 g of an emulsifier, 0.5 g of sodium hydroxide, 18 g of butyl stearate, and 7 g of n-tetradecanol were added to 200 mL of deionized water and stirred to obtain a core material emulsion for later use; (2) Citric acid was added to the core material emulsion to adjust the pH to 3.5, and MF prepolymer was added to the core material emulsion after preheating at 70°C. The reaction was continued for 3 hours to obtain a microcapsule suspension. The microcapsule suspension was filtered, washed and dried to obtain phase change microcapsules.

[0037] Preparation Example 5 The difference between this preparation example and preparation example 4 is that in step (1) of preparing the phase change microcapsules, 15 g of hydrophobic nano-silica sol is also added when preparing the core material emulsion.

[0038] The hydrophobic nano-silica sol was prepared as follows: TEOS, water, isopropyl alcohol, acetic acid, methyl acetate, and hexamethyldisilazane were mixed in a volume ratio of 1:1.5:5.5:0.3:3.5:0.1:0.4, and the mixture was stirred and reacted at 55° C. for 5 hours to obtain a hydrophobic nano-silica sol. Example

[0039] Examples 1-5 The following description will be made using Example 1 as an example.

[0040] Example 1 In this embodiment, the additives include a defoamer, a viscosity regulator, a film-forming aid, and a dispersant in a weight ratio of 3.5:7:5:1. The defoamer is a commercially available silicone defoamer, the viscosity regulator is a mixture of Amp-95 and Dow thickener ASE-60 in a weight ratio of 1:6, the film-forming aid is a texanol additive provided by Eastman Chemical, and the dispersant is a 5040 general dispersant; the filler includes carbon black (T industry grade, ORION No. 6); the self-dispersing graphene is prepared according to the method of Preparation Example 1, the styrene-acrylic emulsion is prepared according to the method of Preparation Example 2, the phase change microcapsules are prepared according to the method of Preparation Example 4, and the polyethylene glycol is PEG2000.

[0041] This embodiment provides a graphene heat dissipation coating with phase change heat storage function, including the following components in parts by weight: 400g of styrene acrylic emulsion, 100g of deionized water, 33g of additive, 55g of polyethylene glycol, 80g of filler, 30g of phase change microcapsules, and 6.5g of self-dispersed graphene.

[0042] As shown in Table 1, the main difference between Examples 1-5 is that the raw material ratios of the graphene heat dissipation coating are different.

[0043] Table 1 Raw material ratio of graphene heat dissipation coating Example 6 The difference between this embodiment and embodiment 5 is that the styrene acrylic emulsion is prepared according to the method of preparation example 3.

[0044] Example 7 The difference between this embodiment and embodiment 6 is that the auxiliary agent further includes hydroxyethyl cellulose, and the amount of hydroxyethyl cellulose used is 2.5 g.

[0045] Example 8 The difference between this embodiment and embodiment 7 is that the components of the graphene heat dissipation coating further include nano-lignin, and the amount of nano-lignin used is 5 g.

[0046] Example 9 The difference between this embodiment and embodiment 8 is that the components of the graphene heat dissipation coating further include hydrolyzed gelatin (CAS: 68410-45-7), and the amount of hydrolyzed gelatin used is 3.5 g.

[0047] Example 10 The difference between this embodiment and embodiment 9 is that the phase change microcapsules are prepared according to the method of preparation example 5.

[0048] Comparative Example Comparative Example 1 This comparative example provides a carbon nanotube radiant heat dissipation coating, prepared as follows: carbon nanotubes NC7000 and aqueous dispersant UT3501 were weighed in appropriate proportions to prepare a mixed aqueous solution having a carbon nanotube content of 3.0% and a solids content of 5.0%. A BYK wetting agent equivalent to 1% of the total weight of the mixed aqueous solution was added, and the mixture was allowed to stand for 12 hours. The mixture was then ground in a sand mill for 30-60 minutes to form a uniform carbon nanotube dispersion. The carbon nanotube dispersion was then mixed with aqueous polyurethane resin ADMZ709, controlling the carbon nanotube content to 10% of the total solids content, to produce the radiant heat dissipation coating.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that the components of the graphene heat dissipation coating do not include polyethylene glycol.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that the components of the graphene heat dissipation coating do not include fillers.

[0051] Comparative Example 4 The difference between this comparative example and Example 1 is that the components of the graphene heat dissipation coating do not include phase change microcapsules.

[0052] Comparative Example 5 The difference between this comparative example and Example 1 is that the phase change microcapsules do not contain nano-iron oxide.

[0053] Comparative Example 6 This comparative example differs from Example 1 in that the self-dispersed graphene is replaced with graphene of the same weight.

[0054] Performance testing methods Test preparation: The coating was evenly coated on the surface of the aluminum foil using an automatic coating apparatus (Hefei Kejing Material Technology Co., Ltd., MSK-AFA-Ⅲ) with a scraping thickness of 15 μm. After the coating was dry, it was placed in an oven at 100°C for 10 minutes and then cut into 35 mm × 35 mm square specimens for evaluation of heat dissipation performance.

[0055] Test steps: A 24V electric heating ceramic sheet (25mm × 10mm × 1.2mm) was used as the heat source. The sample coated on the aluminum foil was cut into a 35mm × 35mm size. The electric heating ceramic sheet was attached to the center of the aluminum foil using thermally conductive silicone resin. Aluminum foil without heat dissipation coating served as a reference sample. The test sample and reference sample were connected in series and powered by a 0.2A constant current DC power supply. A contact thermometer was used to measure the temperature of the test sample and reference sample 30 minutes after power was applied. The absolute value of the temperature difference between the two samples was calculated and recorded as the heat dissipation amplitude. The results are shown in Table 2.

[0056] Table 2 Heat dissipation range sample Heat dissipation range / ℃ sample Heat dissipation range / ℃ Example 1 13.7 Example 9 15.0 Example 2 13.7 Example 10 15.4 Example 3 13.8 Comparative Example 1 8.7 Example 4 13.9 Comparative Example 2 11.3 Example 5 14.0 Comparative Example 3 11.7 Example 6 14.3 Comparative Example 4 10.4 Example 7 14.5 Comparative Example 5 12.2 Example 8 14.8 Comparative Example 6 12.5 Combining Examples 1-5 with Comparative Example 1 and Table 2, it can be seen that the heat dissipation amplitudes measured in Examples 1-5 are all greater than those in Comparative Example 1. This is because Examples 1-5 can absorb heat through the evenly distributed polyethylene glycol and phase change microcapsules, achieve efficient heat transfer, and furthermore, carbon black can synergistically enhance the radiative heat dissipation of the coating with the self-dispersed graphene. The coating formed by the graphene heat dissipation coating of the present application can efficiently absorb heat through phase change energy storage and is also more easily heat exchanged with the air, thereby effectively suppressing the temperature rise of electronic devices and helping to maintain the stable operation of electronic devices.

[0057] Combining Example 1 and Comparative Example 2 and Table 2, it can be seen that the heat dissipation amplitude measured in Example 1 is greater than that in Comparative Example 2. This is because Comparative Example 2 lacks polyethylene glycol and cannot fully realize the phase change heat storage function, resulting in poor heat dissipation effect. Therefore, the temperature difference between the tested sample and the comparative reference sample is small.

[0058] Combining Example 1 and Comparative Example 3 with Table 2 reveals that Example 1 achieved a greater heat dissipation amplitude than Comparative Example 3. This is due to the lack of filler in Comparative Example 3, which prevents the synergistic effect of carbon black and self-dispersible graphene. The lack of filler not only hinders heat transfer but also weakens the coating's ability to radiate heat, resulting in a smaller temperature difference between the tested sample and the reference sample.

[0059] Combining Example 1 and Comparative Example 4 with Table 2, it can be seen that the heat dissipation amplitude measured in Example 1 is greater than that in Comparative Example 4. This is because Comparative Example 3 lacks phase change microcapsules and cannot fully realize the phase change heat storage function, resulting in poor heat dissipation effect. Therefore, the temperature difference between the tested sample and the comparative reference sample is small.

[0060] Combining Example 1 and Comparative Example 5 and Table 2, it can be seen that the heat dissipation amplitude measured in Example 1 is greater than that in Comparative Example 5. This is because Comparative Example 5 lacks nano-iron oxide, and the heat is greatly hindered when transferring to the phase change microcapsules, and the phase change heat storage function cannot be fully realized, resulting in poor heat dissipation effect. Therefore, the temperature difference between the tested sample and the comparative reference sample is small.

[0061] Combining Example 1 and Comparative Example 6 with Table 2, it can be seen that the heat dissipation amplitude measured in Example 1 is greater than that in Comparative Example 6. This is because the graphene in Comparative Example 6 has not been modified and will agglomerate, and cannot fully achieve synergistic cooperation with carbon black, resulting in poor heat dissipation effect of the coating. Therefore, the temperature difference between the tested sample and the comparative reference sample is small.

[0062] Combining Example 5 and Example 6 with Table 2, it can be seen that the heat dissipation amplitude measured in Example 6 is greater than that in Example 5. This is because the lignin groups introduced by the lignin-based acrylate can form hydrogen bonds with polyethylene glycol. The hydrogen bonds can enhance the interchain coupling to form a continuous thermal network, thereby providing a richer heat transfer pathway, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the effect of the coating in suppressing temperature rise.

[0063] Combining Example 6 and Example 7 with Table 2, it can be seen that the heat dissipation amplitude measured in Example 7 is greater than that in Example 6. This is because hydroxyethyl cellulose can increase the hydrogen bond density inside the coating, providing a richer heat transfer pathway, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0064] Combining Example 7 and Example 8 and Table 2, it can be seen that the heat dissipation amplitude measured in Example 8 is greater than that in Example 7. This is because the oxygen-containing groups in the nano-lignin can effectively increase the hydrogen bond density inside the coating, and the lignin-based acrylate makes the nano-lignin and styrene acrylic emulsion have good compatibility, which promotes the uniform dispersion of the nano-lignin, thereby providing a richer heat transfer pathway, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0065] Combining Example 8 and Example 9 with Table 2, it can be seen that the heat dissipation amplitude measured in Example 9 is greater than that in Example 8. This is because the amino and carboxyl groups in the hydrolyzed gelatin can increase the hydrogen bond density inside the coating, providing a richer heat transfer pathway, so that heat can be efficiently transferred to the phase change microcapsules and polyethylene glycol, which helps to improve the coating's effect of suppressing temperature rise.

[0066] Combining Example 9 and Example 10 and Table 2, it can be seen that the heat dissipation amplitude measured in Example 10 is greater than that in Example 9. This is because the nano-silica particles in the hydrophobic nano-silica sol have good compatibility with the tetradecanol and butyl stearate in the capsule core. The nano-silica particles can enhance the thermal conductivity of the capsule core, making it easier for heat to diffuse in the capsule core, thereby improving the heat absorption efficiency of the phase change microcapsules and helping to improve the effect of the coating in suppressing temperature rise.

[0067] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application as needed without any creative contribution. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A graphene heat dissipation coating with phase change heat storage function, characterized in that: The coating comprises the following components in parts by weight: 400-410 parts of styrene-acrylic emulsion, 100-110 parts of deionized water, 33-35 parts of additives, 55-70 parts of polyethylene glycol, 80-90 parts of fillers, 30-35 parts of phase-change microcapsules, and 6.5-7.5 parts of self-dispersed graphene; the additives comprise a defoaming agent, a viscosity regulator, a film-forming aid, and a dispersant; the filler comprises carbon black; and the capsule wall components of the phase-change microcapsules comprise melamine resin and nano-iron oxide.

2. The graphene heat dissipation coating with phase change heat storage function according to claim 1, characterized in that: The self-dispersed graphene is prepared according to the following method: (1) adding graphene oxide to deionized water and performing ultrasonic dispersion to obtain a graphene dispersion, adding a CTAB aqueous solution to the graphene dispersion and heating the mixture to react, thereby obtaining CTAB-modified graphene oxide; (2) CTAB-modified graphene oxide is dispersed in an organic solvent, a Grignard reagent is added, and condensation reflux is performed under heating conditions in a water bath while continuously stirring. After the reaction is completed, the product is filtered, and the product is washed and dried to obtain self-dispersed graphene.

3. The graphene heat dissipation coating with phase change heat storage function according to claim 1, characterized in that: Described styrene acrylic emulsion is prepared according to the following method: (1) preparing an emulsifier solution, an initiator solution and a monomer mixture for standby use; in this step, the monomers used to prepare the monomer mixture include acrylic acid, styrene, butyl acrylate and isooctyl acrylate; (2) Add a portion of the monomer mixture to the emulsifier solution, stir and emulsify, then add a portion of the initiator solution under heating conditions in a water bath, and continue to heat and react to obtain an intermediate dispersion; (3) The remaining monomer mixture and initiator solution are added to the intermediate dispersion, and the reaction is continued at a temperature of 100 °C. After the reaction is completed, the temperature is lowered and ammonia water is added to adjust the pH. After discharging, a styrene-acrylic emulsion is obtained.

4. The graphene heat dissipation coating with phase change heat storage function according to claim 3, characterized in that: In the method for preparing the styrene acrylic emulsion, the monomers used to prepare the monomer mixture further include lignin-based acrylate.

5. The graphene heat dissipation coating with phase change heat storage function according to claim 4, characterized in that: The lignin-based acrylate is prepared according to the following method: Alkali lignin, methylimidazole and methacrylic anhydride are mixed, stirred for reaction, and the product is added into hexane. The precipitate is collected, and the precipitate is dissolved in dichloromethane. The precipitate is washed with deionized water, and then precipitated again with hexane. The obtained precipitate is dried to obtain lignin-based acrylate.

6. The graphene heat dissipation coating with phase change heat storage function according to claim 4, characterized in that: The auxiliary agent also includes hydroxyethyl cellulose.

7. The graphene heat dissipation coating with phase change heat storage function according to claim 6, characterized in that: The components of the graphene heat dissipation coating also include nano-lignin.

8. The graphene heat dissipation coating with phase change heat storage function according to claim 7, characterized in that: The components of the graphene heat dissipation coating also include hydrolyzed gelatin.

9. The graphene heat dissipation coating with phase change heat storage function according to claim 1, characterized in that: The phase change microcapsules are prepared according to the following method: (1) Melamine, formaldehyde, nano-iron oxide and deionized water are mixed, preheated and triethanolamine is added to adjust the pH, and then the mixture is kept warm for reaction to obtain MF prepolymer for later use; SMA, emulsifier, sodium hydroxide, butyl stearate and n-tetradecanol are added to deionized water and stirred to obtain core material emulsion for later use; (2) Citric acid is added to the core material emulsion to adjust the pH, and MF prepolymer is added to the core material emulsion after preheating. After heat preservation and reaction, a microcapsule suspension is obtained. The microcapsule suspension is filtered, washed and dried to obtain phase change microcapsules.

10. The graphene heat dissipation coating with phase change heat storage function according to claim 9, characterized in that: In the step (1) of preparing the phase-change microcapsules, hydrophobic nano-silica sol is also added when preparing the core material emulsion.

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