Water-based graphene heat dissipation coating, preparation method thereof and graphene heat dissipation coating

Abstract

The invention discloses a water-based graphene heat dissipation coating, a preparation method thereof and a graphene heat dissipation coating. The water-based graphene heat dissipation coating comprises the following components: a water-based epoxy resin emulsion, graphene water-based slurry, a functional additive, a curing agent and water. The preparation method comprises the following steps: uniformly dispersing graphene water-based slurry, water and a functional additive, sequentially adding a water-based epoxy resin emulsion and a curing agent, and uniformly mixing to obtain the water-based graphene heat dissipation coating. The water-based graphene heat dissipation coating provided by the invention is good in heat conductivity, and a graphene heat dissipation coating prepared from the water-based graphene heat dissipation coating has the advantages of high heat dissipation and high wear resistance, and also has the characteristics of environmental protection and no toxicity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat dissipation coatings, and particularly relates to a water-based graphene heat dissipation coating, a preparation method thereof and a graphene heat dissipation coating. BACKGROUND

[0002] The heat dissipation coating technology can enhance the heat radiation capacity of a device and strengthen the heat exchange between the device and the outside without changing the original structure of the device, and is an easy and effective method for dissipating heat of the device. Generally, the heat dissipation coating mainly uses a polymer as a base material, and adds some metal, metal oxide and metal nitride fillers with good heat conduction performance, such as gold, copper, aluminum, aluminum oxide and boron nitride. However, the heat dissipation performance of the heat dissipation coating is not good, and the hardness, adhesion and weather resistance cannot meet the requirements.

[0003] Graphene is a two-dimensional sheet material with a six-membered ring structure formed by sp2 hybridization of carbon. The thermal conductivity of pure and defect-free graphene is as high as 5300 W / (m·K), and the mechanical properties and corrosion resistance are excellent. At present, the urgent problem is how to select graphene to control the proportion of heat conduction and heat radiation in the medium and low temperature environment of the equipment to obtain high heat dissipation efficiency. Patent CN116042039A provides a graphene heat dissipation damping coating and a preparation method thereof. The graphene heat dissipation coating is prepared by adding graphene modified water-based acrylic emulsion and modified graphene oxide. However, the graphene is covered by a silicon-containing compound, which affects the heat conduction performance. In the preparation of graphene aqueous solution and the modification of graphene oxide, a large amount of organic solvent is used, which has a great impact on the environment. Patent CN114479614A prepares a water-based graphene composite heat dissipation coating by adding reduced graphene oxide and water-based epoxy resin. However, the graphene obtained by high temperature and high pressure reduction of graphene oxide has low purity and weak performance compared with pure graphene, and is also prone to have other functional groups. Patent CN117586687A prepares a graphene heat dissipation coating by adding expanded graphene and resin. However, the expanded graphene has large porosity, discontinuous and incomplete sheet layer, and low density, which affects the heat conduction and dispersibility.

[0004] Therefore, how to improve the heat dissipation effect of the graphene heat dissipation coating and ensure environmental safety is a technical problem to be solved in the field. SUMMARY

[0005] The main purpose of the present application is to provide a water-based graphene heat dissipation coating, a preparation method thereof and a graphene heat dissipation coating to overcome the shortcomings of the prior art.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include: The first aspect of the present application provides a water-based graphene heat dissipation coating, which comprises the following components: a water-based epoxy resin emulsion, a graphene water-based slurry, a functional additive, a curing agent and water.

[0007] In some embodiments, the water-based graphene heat dissipation coating comprises the following components by weight fraction: 10-50 parts of a water-based epoxy resin emulsion, 1-20 parts of a graphene water-based slurry, 0.1-1 part of a functional additive, 0.1-1 part of a curing agent, and 2-15 parts of water.

[0008] The second aspect of the present application provides a preparation method of the above-mentioned water-based graphene heat dissipation coating, which comprises: uniformly mixing the graphene water-based slurry with the water-based epoxy resin, adding the functional additive, uniformly dispersing, and then adding the curing agent to obtain the water-based graphene heat dissipation coating.

[0009] The third aspect of the present application provides a graphene heat dissipation coating layer obtained by coating and curing the above-mentioned water-based graphene heat dissipation coating.

[0010] Compared with the prior art, the present application has at least the following beneficial effects: (1) The water-based graphene heat dissipation coating prepared by the present application uses a water-based epoxy resin as the main film-forming component, and the water-based epoxy resin can fill the gaps of small flake graphene, make the graphene lap uniform, compensate for the shortcomings of small flake graphene in thermal conductivity, and has better dispersibility than large flake graphene. The synergistic effect of thin layer graphene in heat conduction and heat dissipation significantly improves the thermal conductivity of the coating. The graphene heat dissipation coating prepared therefrom has the advantages of high heat dissipation and high wear resistance, and also has the characteristics of environmental protection and non-toxicity.

[0011] (2) The water-based epoxy resin emulsion prepared by the present application, through the specific combination of epoxy resin and other components, obtains an emulsified water-based epoxy resin, which can better insert into the interlayer of graphene, connect the graphene and graphene together, and make the heat conduction channel more continuous, better play the excellent heat conduction and heat dissipation characteristics of graphene; and the water-based epoxy resin of the present application also has hydrophilic properties, which is more suitable for mixing with the graphene water-based slurry.

[0012] (3) The preparation method of the graphene water-based slurry provided by the present application obtains a graphene water-based slurry with high solid content and low flake size through a unique ultrahigh pressure homogenization process; and by adding a dispersant and a stabilizer, the problem of easy agglomeration of the graphene water-based slurry during long-term storage and the difficulty of re-dispersing application are solved. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0014] Figure 1 Figure 1 is an electron scanning image of graphene in the graphene aqueous slurry in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0015] In view of the problems in the prior art, the present application provides a water-based graphene heat dissipation coating, a preparation method thereof and a graphene heat dissipation coating, which mainly uses water-based epoxy resin as the main film-forming component, cooperates with the synergistic effect of heat conduction and heat dissipation of thin-layer graphene, and significantly improves the thermal conductivity coefficient of the graphene heat dissipation coating, and has the advantages of high heat dissipation and high wear resistance.

[0016] The technical solutions, implementation processes and principles thereof will be further explained and described as follows.

[0017] The first aspect of the present application provides a water-based graphene heat dissipation coating, which comprises the following components: water-based epoxy resin emulsion, graphene aqueous slurry, functional additives, curing agent and water.

[0018] In some embodiments, the water-based graphene heat dissipation coating comprises the following components in terms of weight fraction: water-based epoxy resin emulsion 10-50 parts, graphene aqueous slurry 1-20 parts, functional additives 0.1-1 part, curing agent 0.1-1 part, and water 2-15 parts.

[0019] In some embodiments, the solid content of the water-based graphene heat dissipation coating is 10%-30%.

[0020] In some embodiments, the solid content of the water-based epoxy resin emulsion is 50%-75%.

[0021] In some embodiments, the solid content of the graphene aqueous slurry is 5-20%.

[0022] In some embodiments, the flake diameter of graphene in the water-based graphene heat dissipation coating is 0.1-3 μm, and the number of flake layers is 1-10 layers.

[0023] In some embodiments, the graphene aqueous slurry comprises the following components in terms of weight fraction: graphene 5-15 parts, dispersant 0.1-1 part, stabilizer 0.025-5 parts, and water 80-95 parts.

[0024] In some embodiments, the epoxy resin in the aqueous epoxy resin emulsion comprises any one of bisphenol A type epoxy resin or bisphenol F type epoxy resin.

[0025] In some preferred embodiments, the epoxy equivalent weight of the epoxy resin is 100-900 g / eq.

[0026] In some embodiments, the functional additives comprise defoaming agents, film forming agents, anti-rust agents, and leveling agents.

[0027] In some preferred embodiments, the defoaming agents comprise, but are not limited to, polydimethylsiloxane, polyether-modified silicone oil.

[0028] In some preferred embodiments, the film forming agents comprise alcohol esters or alcohol ethers.

[0029] In some preferred embodiments, the anti-rust agents comprise, but are not limited to, hexamethylenetetramine, sodium citrate, sodium dodecylbenzenesulfonate.

[0030] In some preferred embodiments, the leveling agents comprise at least any one of, but are not limited to, organically modified siloxane, acrylate copolymer, silicone leveling agent, high molecular weight polydimethylsiloxane, fluorocarbon polymer compound, etc.

[0031] In a typical embodiment, the mass ratio of the defoaming agent, film forming agent, anti-rust agent, and leveling agent in the functional additives is 3:3:2:2.

[0032] In some embodiments, the curing agent comprises at least any one of, but is not limited to, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, etc.

[0033] In some embodiments, the water comprises, but is not limited to, deionized water.

[0034] The second aspect of the present application provides a method for preparing the above-mentioned aqueous graphene heat dissipation coating, which comprises: uniformly mixing the aqueous graphene slurry with the aqueous epoxy resin, adding the functional additives, uniformly dispersing, and then adding the curing agent to obtain the aqueous graphene heat dissipation coating.

[0035] In some embodiments, the method for preparing the aqueous epoxy resin emulsion comprises: mixing the epoxy resin, emulsifier, and non-aqueous solvent at 80-90 ℃, stirring for 20-40 min, high-speed shearing for 20-40 min to obtain a uniform emulsion, then adding water to the uniform emulsion within 0.5 h-1 h by phase inversion method, stirring for 7-9 h when the solid content reaches 50%-75% to obtain the aqueous epoxy resin emulsion.

[0036] The epoxy resin itself is lipophilic and insoluble in water but only soluble in some organic solvents (such as acetone, propylene glycol methyl ether, etc.). The phase inversion method is to first stir the epoxy resin and emulsifier uniformly and completely, then slowly add water to the epoxy resin under high shear force, so that the epoxy system is converted from water-in-oil (W / O) to oil-in-water (O / W), and finally a stable and uniform aqueous epoxy emulsion is formed. In addition, by emulsifying and modifying the epoxy resin with an emulsifier, the viscosity of the epoxy resin is reduced, making the high-speed shear emulsification process easier to perform, and an epoxy resin water dispersion system with good stability is obtained.

[0037] In the preparation method of the aqueous epoxy resin emulsion of the present application, the specific formula of the aqueous epoxy resin and the selected combination of each component are used to obtain the emulsified aqueous epoxy resin, which can better insert into the interlayer of graphene, connect graphene and graphene together, and make the heat conduction channel more continuous. The hydrophilic property of the aqueous epoxy resin of the present application is more suitable for mixing with the aqueous graphene slurry.

[0038] Further, the mass ratio of the epoxy resin, the emulsifier, the non-aqueous solvent and water is 0.5-0.75: 0.01-0.2: 0.2-0.25: 0.2-0.25.

[0039] Further, the mass ratio of the water and the epoxy resin is 1:2-1:4.

[0040] Further, the emulsifier includes at least any one of Tween 20, Tween 60, Tween 80, Span 60, Span 80, OP10, sodium dodecyl sulfonate, and sodium dodecyl benzene sulfonate.

[0041] Further, the non-aqueous solvent includes at least any one of n-butanol, isopropyl alcohol, acetone, n-butanone, ethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol butyl ether, cyclohexane, and ethyl acetate.

[0042] Further, the shear speed of the high-speed shear treatment is 2000-8000 rpm.

[0043] In some embodiments, the preparation method of the aqueous graphene slurry includes: after the graphite and the dispersant are subjected to high-speed shear treatment for 20-40 min, the graphite is subjected to ultrahigh pressure homogenization at 5-25 ℃ for 3-6 times at 60-150 Mpa, and then a stabilizer is added, and the aqueous graphene slurry is prepared after uniform mixing.

[0044] In the preparation method of the graphene aqueous slurry, pure graphite is directly used as raw material and is processed by the ultra-high pressure homogenization method, so that the prepared graphene can be well dispersed in water and has a high solid content of 5-20%. Compared with the graphene oxide and reduced graphene oxide in the prior art, the graphene has high purity, is not affected by other functional groups and has good performance.

[0045] Further, the mass ratio of the graphite, the dispersant and the water is 5-20:0.1-0.5:80.5-95.

[0046] Further, the dispersant includes at least any one of polyvinyl alcohol, polyvinylpyrrolidone, sodium dodecyl benzene sulfonate and sodium lignosulfonate.

[0047] Further, the stabilizer includes at least any one of modified polyurea solution, xanthan gum, carrageenan, hydroxymethyl cellulose, guar gum and gelatin.

[0048] The third aspect of the application provides a graphene heat dissipation coating layer obtained by coating and curing the above aqueous graphene heat dissipation coating.

[0049] In some embodiments, the thickness of the graphene heat dissipation coating layer is 5-50 microns.

[0050] In some embodiments, the thermal conductivity of the graphene heat dissipation coating layer is >10 W / m·K.

[0051] In some embodiments, the wear rate of the graphene heat dissipation coating layer is <2.5%.

[0052] In the present application, the graphene in the graphene aqueous slurry is stably dispersed in water, only containing a trace amount of dispersant and stabilizer, and an ultrahigh pressure homogenization device is used in the preparation process to not only break the graphene particle size, but also to shear and thin the thickness (the actual pressure is greater than 200 MPa, and few existing technologies can break the slurry with particles at this pressure), thereby obtaining a graphene aqueous slurry with small particle size, high solid content and thin thickness, wherein the graphene has a small sheet size (0.1 μm~3 μm) and a high solid content of 5~20%. The graphene with small sheet size has good dispersibility, and the larger the sheet size, the more likely it is to agglomerate and difficult to disperse again. Small sheet size is easy to disperse again, but the thermal conductivity is weaker than that of large sheet size due to the increased boundary. However, the present application relies on the water-based epoxy resin to fill the boundary of small sheet size graphene, making the graphene lap uniform, which can make up for the disadvantage of small sheet size graphene that is not as good as large sheet size in thermal conductivity, and has better dispersibility than large sheet size. At the same time, the same amount of few-layer and thin-layer graphene can build a higher connectivity thermal conduction network structure. Moreover, when the water-based graphene heat dissipation coating is coated as a coating, the water in the water-based slurry is removed, which does not affect the overall technical effect.

[0053] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. Those skilled in the art can modify or replace the equivalent without departing from the spirit and scope of the present application, which should be covered within the protection scope of the present application.

[0054] In the examples, the specific experimental steps or conditions are not specified, which can be performed according to the conventional experimental steps described in the literature or the operation or conditions. The reagents or instruments used are not specified by the manufacturer, which can be obtained by market purchase. The remaining raw materials and instruments not mentioned are commercially available, which are conventional choices and do not involve the core technical means of the present application.

[0055] Example 1 The present embodiment provides a preparation method of a water-based graphene heat dissipation coating and a graphene heat dissipation coating, comprising the following steps: (1) Preparation of water-based epoxy resin emulsion, including the following steps: at a temperature of 80-90 ℃, 10 kg of epoxy resin E44 is added into 5 kg of ethyl acetate, then 0.10 kg of Tween80 is added, and stirred for 20-40 min to obtain a uniform dispersion, then 4.8 kg of deionized water is added into the dispersion at a speed of 0.1 L / min by using a peristaltic pump through a phase inversion method, the dispersion becomes viscous first, and is treated by high-speed shearing at a speed of 2000 rpm until the viscosity of the emulsion changes suddenly, then appropriate deionized water is added, and stirring is performed for 8 h until the solid content reaches 50%, and the water-based epoxy resin emulsion is obtained after cooling; (2) Preparation of graphene water-based slurry, including the following steps: 1.8 kg of commercially available graphite is added into 18 kg of deionized water, then 0.1 kg of dispersant polyvinylpyrrolidone is added, and high-speed shearing is performed for 30 min; at a temperature of 5-25 ℃, the high-speed sheared graphite is added into a high-pressure homogenizer, and is homogenized at 30 MPa for 2 times and then at 120 MPa for 3 times; then the homogenized product is transferred into a stirred tank, and 0.1 kg of hydroxymethyl cellulose is added as a stabilizer and stirred uniformly. The graphene in the prepared graphene water-based slurry is as shown in Figure 1 .

[0056] (3) Preparation of water-based graphene heat dissipation coating, including the following steps: 20 kg of graphene water-based slurry is added into a mixing tank, 10 kg of water-based epoxy resin emulsion is added under a rotation speed of 1000 r / min, stirring is performed for 15 min, and 0.1 kg of functional additives is added, the functional additives are defoaming agent, film forming agent, anti-rust agent, and leveling agent, and the mass ratio is 3:3:2:2, the defoaming agent is silicone defoaming agent, the film forming agent is dodecanol ester, the anti-rust agent is hexamethylenetetramine and sodium citrate, and the leveling agent is water-based silicone leveling agent BYK-381; after uniform dispersion and stirring, the water-based heat dissipation coating is obtained. In the preparation process of the water-based graphene heat dissipation coating, a curing agent is finally added, the curing agent is diethylenetriamine, and stirring is continuously performed for 15 min to obtain the curable water-based graphene heat dissipation coating. The mass ratio of water-based epoxy resin emulsion: graphene water-based slurry: functional additives: curing agent: deionized water is 10:20:0.1:0.2:5.

[0057] Example 2 The preparation method of the water-based graphene heat dissipation coating provided in the example is different from that of example 1 in that the raw material ratio of the graphene heat dissipation coating is different, and the solid content of the water-based epoxy resin emulsion and the graphene water-based slurry is unchanged, and the mass ratio of water-based epoxy resin emulsion: graphene water-based slurry: functional additives: curing agent: deionized water is 10:1:0.1:0.1:5. The raw material ratio is shown in Table 1.

[0058] Example 3 The preparation method of the water-based graphene heat dissipation coating provided in this example differs from that of Example 1 in that the raw material ratio of the graphene heat dissipation coating is different. In the case where the solid contents of the water-based epoxy resin emulsion and the graphene water-based slurry are unchanged, the mass ratio of the water-based epoxy resin emulsion: graphene water-based slurry: functional additive: curing agent: deionized water is 50:20:0.8:0.5:10. The raw material ratio is shown in Table 1.

[0059] Example 4 The preparation method of the water-based graphene heat dissipation coating provided in this example differs from that of Example 1 in that the raw material ratio of the graphene heat dissipation coating is different. In the case where the solid contents of the water-based epoxy resin emulsion and the graphene water-based slurry are unchanged, the mass ratio of the water-based epoxy resin emulsion: graphene water-based slurry: functional additive: curing agent: deionized water is 20:5:0.1:0.4:2.5. The raw material ratio is shown in Table 1.

[0060] Example 5 The preparation method of the water-based graphene heat dissipation coating provided in this example differs from that of Example 1 in that the raw material ratio of the graphene heat dissipation coating is different. In the case where the solid contents of the water-based epoxy resin emulsion and the graphene water-based slurry are unchanged, the mass ratio of the water-based epoxy resin emulsion: graphene water-based slurry: functional additive: curing agent: deionized water is 30:15:0.15:0.6:5. The raw material ratio is shown in Table 1.

[0061] Example 6 The preparation method of the water-based graphene heat dissipation coating provided in this example differs from that of Example 1 in that the raw material ratio of the graphene heat dissipation coating is different. In the case where the solid contents of the water-based epoxy resin emulsion and the graphene water-based slurry are unchanged, the mass ratio of the water-based epoxy resin emulsion: graphene water-based slurry: functional additive: curing agent: deionized water is 20:20:0.2:0.4:7.5. The raw material ratio is shown in Table 1.

[0062] Table 1: Contents of each raw material of the graphene heat dissipation coating (unit: kg)

[0063] Example 7 The preparation method of the water-based graphene heat dissipation coating provided in this example differs from that of Example 1 in that, in the preparation of the graphene water-based slurry, an equal amount of polyvinyl alcohol is used as the dispersant.

[0064] Example 8 The preparation method of the water-based graphene heat dissipation coating provided in this embodiment is different from that in Embodiment 1 in that, in the preparation of the graphene water-based slurry, the same amount of modified polyurea is used as the stabilizer.

[0065] Embodiment 9 The preparation method of the water-based graphene heat dissipation coating provided in this embodiment is different from that in Embodiment 1 in that, in the preparation of the graphene water-based slurry, after the raw materials are added in proportion, the graphene with smaller particle size and thinner sheet layer is obtained by treating the mixture in an ultrahigh-pressure homogenizer at 180 Mpa for 3 times. The particle size of the graphene is 0.1-2 μm, and the number of sheet layers is about 1-10.

[0066] Embodiment 10 The preparation method of the water-based graphene heat dissipation coating provided in this embodiment is different from that in Embodiment 1 in that, in the preparation of the water-based epoxy resin emulsion, the same amount of propylene glycol methyl ether is used as the non-water solvent.

[0067] Embodiment 11 The preparation method of the water-based graphene heat dissipation coating provided in this embodiment is different from that in Embodiment 1 in that, in the preparation of the water-based epoxy resin emulsion, the same amount of E51 is used as the epoxy resin.

[0068] Embodiment 12 The preparation method of the water-based graphene heat dissipation coating provided in this embodiment is different from that in Embodiment 1 in that, in the preparation of the water-based epoxy resin emulsion, the same amount of OP10 is used as the emulsifier.

[0069] Comparative Example 1 The preparation method of the water-based graphene heat dissipation coating provided in this comparative example is different from that in Embodiment 1 in that, the same amount of deionized water is used to replace the graphene water-based slurry.

[0070] Comparative Example 2 The preparation method of the water-based graphene heat dissipation coating provided in this comparative example is different from that in Embodiment 1 in that, the same amount of graphene oxide is used to replace the graphene in the graphene water-based slurry.

[0071] Comparative Example 3 The preparation method of the water-based graphene heat dissipation coating provided in this comparative example is different from that in Embodiment 1 in that, the same amount of water-based polyacrylic acid emulsion is used to replace the water-based epoxy resin emulsion.

[0072] Comparative Example 4 The preparation method of the water-based graphene heat dissipation coating provided in this comparative example is different from that in Embodiment 1 in that, the mass ratio of the water-based epoxy resin emulsion, the graphene water-based slurry, the functional additive, the curing agent and the deionized water is 50:0.5:0.1:0.2:5.

[0073] Comparative Example 5 The preparation method of the aqueous graphene heat dissipation coating provided by the present comparative example is different from that of Example 1 in that a common ordinary homogenizing device on the market is used to crush the graphite.

[0074] Performance test The graphene heat dissipation coating prepared in Examples 1-12 and Comparative Examples 1-5 was taken respectively, and then a layer of graphene heat dissipation coating was coated on a metal aluminum plate to obtain a dry film with a thickness of 20 μm. The dry film was used as a sample and the following performance test was carried out, and the test results are shown in Table 2.

[0075] Pencil hardness test of coating: the hardness of the coating is tested by a pencil hardness tester. For the pencil, the lead core of 5-6 mm needs to be leaked out, and the lead core is carefully kept as a cylindrical shape without damage. The test starts from the pencil with the smallest hardness, and the coating is broken by a pencil with a certain hardness value, and the hardness of the coating is the hardness value of the previous pencil. Each group of samples is tested for 3 times to obtain the hardness of the coating of the sample.

[0076] Coating adhesion test: coating adhesion is one of the important indicators of coating. The present application uses QFHA600 and the matching magnifying lens to test. The grating device draws a grid through the coating on the sample to form a grid array pattern, and then the surface is swept back and forth 5 times with a soft brush. The test results are recorded by comparing the standard and observing the surface with a magnifying lens.

[0077] Coating heat dissipation effect: the thermal conductivity of the sample is tested according to ASTM E1530-19. The higher the thermal conductivity, the better the heat dissipation effect of the graphene heat dissipation damping material. At the same time, an infrared temperature measuring instrument is used to test the temperature change of the same coating after 50 s on the heater.

[0078] The wear resistance is tested by the following method: the surface of the sample is rubbed with an abrasive machine, and the sandpaper with a mesh of 1000 is rubbed for 24 h. The wear rate is used to characterize the wear resistance, and the smaller the wear rate, the better the wear resistance of the graphene heat dissipation damping material. Wear rate = (mass before dry film wear-mass after dry film wear) / mass before dry film wear x 100%.

[0079] The water resistance is tested by the following method: the sample is added to water at a temperature of 20-35℃, and the sample is completely soaked and treated for 60 days. The time of bubbling and softening of the sample is observed. The longer the time, the better the water resistance of the graphene heat dissipation material.

[0080] Table 2 Test results of graphene heat dissipation coating

[0081] As can be seen from Table 2, the graphene heat dissipation coating prepared from the water-based graphene heat dissipation coating of the present application has a high thermal conductivity of 10.08-15.68 W / m·K, showing good heat dissipation effect. It also has low wear rate and high water resistance, and does not bubble or soften in water at a temperature of 20-35℃ for 60 days, showing high wear resistance and long-term use stability.

[0082] Comparing Example 1 with Comparative Example 1, it can be seen that adding graphene in the water-based epoxy emulsion can significantly improve the thermal conductivity of the heat dissipation coating and increase the heat dissipation effect of the graphene heat dissipation coating. At the same time, due to the effect of reducing friction and increasing lubrication of graphene, the wear rate is also significantly reduced, and the wear resistance of the graphene heat dissipation coating is enhanced.

[0083] Comparing Example 1 with Comparative Example 2, it can be seen that the effect of adding graphene oxide in the raw material of the graphene heat dissipation coating is not as good as that of directly adding graphene. Because the edge chemical bond of graphene oxide is more prone to breakage, it is more difficult to disperse uniformly in the emulsion, resulting in discontinuity of the heat conduction network in the water-based graphene heat dissipation coating.

[0084] Comparing Example 1 with Comparative Example 3, it can be seen that the water resistance and heat resistance of polyacrylic acid are poorer than those of epoxy resin, resulting in lower service life of the coating.

[0085] Comparing Example 1 with Comparative Example 4, it can be seen that the heat dissipation performance of the coating is greatly reduced because the proportion of added epoxy resin is relatively high.

[0086] Comparing Example 1 with Comparative Example 5, it can be seen that in the process of preparing graphene from graphite by using a common homogenizer, only nano substances can be processed in terms of particle size, and the thickness of graphene changes little, so that an effective heat conduction network cannot be built in the coating, resulting in reduced heat conduction performance and affecting the heat dissipation performance of the coating layer.

[0087] Comparing Example 1 with Example 9, it can be seen that small-particle-size thin-layer graphene has a more excellent effect on heat dissipation of the coating, but too small particle size of graphene is not conducive to the formation of an effective graphene heat conduction network in the structure jointing process when the thickness does not decrease. However, the comprehensive performance of the water-based graphene heat dissipation coating is still good.

[0088] In summary, the water-based graphene heat dissipation coating of the present application has the advantages of heat dissipation, wear resistance, use stability and environmental protection, and shows good comprehensive performance, which can meet the market demand.

[0089] In addition, the inventors of the present application have also made tests with reference to the aforementioned examples, other raw materials, process operations and process conditions described in the present specification, and all have obtained relatively ideal results.

[0090] While the application has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and / or additions can be made without departing from the spirit and scope of the application. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from its scope. Therefore, it is intended that the application not be limited to the disclosed embodiments, but will include all embodiments falling within the scope of the appended claims.

Claims

1. A water-based graphene heat dissipation coating, characterized in that, It includes the following components: waterborne epoxy resin emulsion, graphene waterborne slurry, functional additives, curing agent and water.

2. The water-based graphene heat dissipation coating according to claim 1, characterized in that, It includes the following components by weight: 10-50 parts of waterborne epoxy resin emulsion, 1-20 parts of graphene waterborne slurry, 0.1-1 parts of functional additives, 0.1-1 parts of curing agent, and 2-15 parts of water.

3. The water-based graphene heat dissipation coating according to claim 1, characterized in that: The solid content of the water-based graphene heat dissipation coating is 10-30%; And / or, the solid content of the aqueous epoxy resin emulsion is 50-75%; And / or, the solid content of the graphene aqueous slurry is 5-20%; And / or, the graphene in the aqueous graphene heat dissipation coating has a sheet diameter of 0.1~3μm and a sheet layer number of 1~10 layers; And / or, the graphene aqueous slurry comprises the following components in parts by weight: 5-15 parts graphite, 0.1-1 parts dispersant, 0.025-5 parts stabilizer, and 80-95 parts water; And / or, the epoxy resin in the aqueous epoxy resin emulsion includes either bisphenol A type epoxy resin or bisphenol F type epoxy resin; Preferably, the epoxy equivalent of the epoxy resin is 100~900 g / eq; And / or, the functional additives include defoamers, film-forming agents, rust inhibitors, and leveling agents; Preferably, the defoamer includes at least one of polydimethylsiloxane and polyether-modified silicone oil; Preferably, the film-forming agent includes alcohol esters or alcohol ethers; Preferably, the rust inhibitor includes at least one of hexamethylenetetramine, sodium citrate, and sodium dodecylbenzenesulfonate; Preferably, the leveling agent includes at least one of organic modified siloxane, acrylate copolymer, silicone leveling agent, high molecular weight polydimethylsiloxane, and fluorocarbon polymer compound; And / or, the curing agent includes at least one of diethylenetriamine, triethylenetetraamine, and tetraethylenepentamine; And / or, the water includes deionized water.

4. The preparation method of the water-based graphene heat dissipation coating according to any one of claims 1 to 3, characterized in that, include: A water-based graphene slurry is mixed evenly with a water-based epoxy resin, functional additives are added, and after even dispersion, a curing agent is added to obtain a water-based graphene heat dissipation coating.

5. The preparation method according to claim 4, characterized in that, The method for preparing the aqueous epoxy resin emulsion includes: mixing epoxy resin, emulsifier and non-aqueous solvent at 80~90 °C, stirring for 20~40 min, and high-speed shearing for 20~40 min to obtain a homogeneous emulsion; then adding water to the homogeneous emulsion within 0.5 h~1 h using the phase inversion method; and stirring for 7~9 h when the solid content reaches 50%~75% to obtain the aqueous epoxy resin emulsion.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the epoxy resin, emulsifier, non-aqueous solvent, and water is 0.5~0.75:0.01~0.2:0.2~0.25:0.2~0.25; And / or, the mass ratio of water to epoxy resin is 1:2 to 1:4; And / or, the shearing speed of the high-speed shearing process is 2000~8000 rpm; And / or, the emulsifier includes at least one of Tween20, Tween60, Tween80, Span60, Span80, OP10, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate; And / or, the non-aqueous solvent includes at least one of n-butanol, isopropanol, acetone, n-butanone, ethylene glycol methyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol butyl ether, cyclohexane, and ethyl acetate.

7. The preparation method according to claim 4, characterized in that, The preparation method of the graphene aqueous slurry includes: subjecting the graphite and dispersant to high-speed shearing for 20-40 minutes, then homogenizing them at 5-25°C using an ultra-high pressure homogenization method at 60-180 MPa for 3-6 times, then adding a stabilizer and mixing evenly to obtain the graphene aqueous slurry.

8. The preparation method according to claim 7, characterized in that: The mass ratio of graphite, dispersant and water is 5~20:0.1~0.5:80.5~95; And / or, the dispersant comprises at least one of polyvinyl alcohol, polyvinylpyrrolidone, sodium dodecylbenzene sulfonate, and sodium lignosulfonate; And / or, the stabilizer includes at least one of modified polyurea solution, xanthan gum, carrageenan, sodium carboxymethyl cellulose, guar gum, and gelatin.

9. A graphene heat dissipation coating obtained by curing the water-based graphene heat dissipation coating according to any one of claims 1 to 3.

10. The graphene heat dissipation coating according to claim 9, characterized in that: The thickness of the graphene heat dissipation coating is 5~50μm; And / or, the thermal conductivity of the graphene heat dissipation coating is >10 W / m·K; And / or, the wear rate of the graphene heat dissipation coating is <2.5%.

Images