Graphene electromagnetic shielding coating and preparation method thereof

Abstract

The invention discloses a graphene electromagnetic shielding coating and a preparation method thereof. The graphene electromagnetic shielding coating is obtained by emulsifying and homogenizing the following raw material composition, the raw material composition comprises a solvent and the following components in percentage by mass: 6-10% of graphite powder, 0.3-2% of a dispersing agent and 0.1-1% of a binder. The preparation method comprises the following steps: mixing the raw material compositions to obtain a first solution; emulsifying the first solution to obtain a second solution; and homogenizing the second solution to obtain the graphene electromagnetic shielding coating. According to the graphene electromagnetic shielding coating and the preparation method, the problems that the coating is thick, the cost is high, the conductive filler is easy to settle, the conductivity is attenuated, and the graphene is difficult to disperse stably are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a graphene electromagnetic shielding coating and a preparation method thereof. Background Art

[0002] With the rapid development of the electronic information industry, the use scenarios of various electronic devices are becoming more and more extensive, and the frequency of use is rapidly increasing. High-performance electronic devices are required in many fields including 3C electronic products, 5G equipment, new energy vehicles, military equipment, etc. However, electronic devices with good performance are often accompanied by strong electromagnetic radiation, and different devices may interfere with each other. For example, the processing system of the computer in the automation system will radiate a large amount of electromagnetic waves when working, and the surrounding electronic and electrical equipment is extremely sensitive to electromagnetic radiation. The electromagnetic waves they radiate may interfere with each other, causing the equipment to not work properly. Therefore, the control of electromagnetic pollution is becoming increasingly urgent, and electromagnetic shielding coatings can reduce electromagnetic pollution by reflection and absorption. In addition, electromagnetic shielding coatings are easy to use and have a wide range of applications. Therefore, electromagnetic shielding coatings have received the attention and research of a large number of R&D personnel.

[0003] Commonly used electromagnetic shielding materials in electromagnetic shielding coatings include: metal materials, magnetic materials, carbon-based materials, etc., among which carbon-based materials include graphene and carbon black. Metal materials and magnetic materials have high density and cannot meet the requirements of portable electronic devices for high shielding performance and light weight of electromagnetic shielding coatings. Compared with traditional materials, graphene can break through the original limitations and become a new type of efficient shielding agent. The graphene electromagnetic shielding coating obtained after processing has more outstanding application value in electromagnetic shielding due to its light weight, corrosion resistance and easy processing. The electromagnetic shielding coatings in the prior art have problems such as high density, thick coating, easy sedimentation of conductive fillers, attenuation of conductive performance, high cost, and difficulty in stable dispersion of graphene, which cannot meet the requirements of shielding materials for "thin, light, wide and high". Summary of the invention

[0004] In view of this, the present invention provides a graphene electromagnetic shielding coating and a preparation method, aiming to improve the problems of existing electromagnetic shielding coatings such as high density, thick coating, easy sedimentation of conductive fillers, attenuation of conductive performance, high cost, and difficulty in stable dispersion of graphene.

[0005] The embodiment of the present invention is implemented as follows: a graphene electromagnetic shielding coating is obtained by emulsifying and homogenizing a raw material composition;

[0006] The raw material composition includes the following components:

[0007] Graphite powder, dispersant, binder, solvent;

[0008] The graphite powder includes one or more of ultrafine graphite powder and expanded graphite powder.

[0009] Optionally, in some embodiments,

[0010] The mass percentage of the graphite powder in the raw material composition is 6-10%; and / or

[0011] The mass percentage of the dispersant in the raw material composition is 0.3-2%; and / or

[0012] The mass percentage of the binder in the raw material composition is 0.1-1%.

[0013] Optionally, in some embodiments,

[0014] The graphene includes graphene sheets;

[0015] The number of layers of the graphene sheet is 1-15; and / or

[0016] The diameter of the graphene sheet is 1-5 μm; and / or

[0017] The thickness of the graphene sheet is 1-5 nm.

[0018] Optionally, in some embodiments,

[0019] The ultrafine graphite powder has a mesh size greater than 3000 meshes and a purity greater than 99%; and / or

[0020] The mesh number of the expanded graphite powder is greater than 200 meshes, the purity is greater than 99%, and the expansion multiple is 200 times.

[0021] Optionally, in some embodiments,

[0022] The dispersant includes one or more of polyvinyl pyrrolidone (PVP), sodium lignin sulfonate (SLS), polyoxyethylene lauryl alcohol ether, polyvinyl alcohol (PVA), and Disperbyk-2013.

[0023] Optionally, in some embodiments,

[0024] The binder includes one or more of sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose.

[0025] Optionally, in some embodiments,

[0026] The solvent is water.

[0027] Optionally, in some embodiments,

[0028] The graphene electromagnetic shielding coating has a particle size of 1-5 μm, a fineness of 0.01-3 μm, and a viscosity of 60-200 cps;

[0029] Accordingly, an embodiment of the present invention further provides a method for preparing the graphene electromagnetic shielding coating as described above, comprising:

[0030] Mixing the raw material composition to obtain a first solution;

[0031] emulsifying the first solution to obtain a second solution;

[0032] After the second solution is homogenized, the graphene electromagnetic shielding coating is obtained.

[0033] Optionally, in some embodiments,

[0034] Mixing the raw material composition comprises:

[0035] The raw material composition is stirred at a speed of 200-500 rpm for 1-2 hours at room temperature.

[0036] Optionally, in some embodiments,

[0037] The emulsification speed is 20000-50000 rpm, the time is 0.2-0.5 hour, and the temperature is room temperature.

[0038] Optionally, in some embodiments, the homogenization pressure is 100-140 MPa, the temperature is 25-80° C., and the number of times is 20-80 times.

[0039] The graphene electromagnetic shielding coating of the present invention comprises graphene, a dispersant, a binder and a solvent, and uses graphene as a conductive filler, thereby overcoming the problem of high density of metal materials and magnetic materials as conductive fillers. The graphene electromagnetic shielding coating of the present invention has an electromagnetic shielding effectiveness of more than 85dB in the range of 30MHz-1.5GHz, a volume resistivity of less than 0.007Ω·cm, and a spraying thickness of 0.5-3μm, thereby overcoming the problems of thick coating and high cost. In the process of preparing the graphene electromagnetic shielding coating, ultrafine graphite powder with a mesh size greater than 3000 and a purity greater than 99% and / or expanded graphite powder with a mesh size greater than 200, a purity greater than 99%, and an expansion multiple of 200 times are used, thereby optimizing the parameters of the stirring, emulsifying and homogenizing processes, and solving the problems of easy sedimentation of conductive fillers, attenuation of conductive properties, and difficulty in stable dispersion of graphene. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A method for preparing a graphene electromagnetic shielding coating is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present invention. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0043] In the description of the present invention, the term "including" means "including but not limited to." The terms first, second, third, etc. are used merely as labels and do not impose numerical requirements or establish a sequence.

[0044] In the present invention, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. A and B may be singular or plural.

[0045] In the present invention, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0046] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0047] The technical solution of the present invention is as follows:

[0048] In a first aspect, an embodiment of the present invention provides a graphene electromagnetic shielding coating for electromagnetic shielding of electronic products and other equipment.

[0049] The graphene electromagnetic shielding coating of the present invention is obtained by emulsifying and homogenizing a raw material composition; specifically, the raw material composition includes a solvent and the following components in mass percentage:

[0050] Graphite powder 6-10%, dispersant 0.3-2%, binder 0.1-1%.

[0051] Among them, the mass percentage of graphite powder can be 6.3%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 9.9% and the like; the mass percentage of dispersant can be 0.32%, 0.35%, 0.4%, 0.5%, 0.7%, 1%, 1.15%, 1.3%, 1.4%, 1.5%, 1.7%, 1.9%, 1.95% and the like; the mass percentage of binder can be 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.8%, 0.9%, 0.97% and the like.

[0052] In the graphene electromagnetic shielding coating of the present invention, graphene is formed after graphite powder is processed. Specifically, the graphene is a graphene sheet, the number of layers of the graphene sheet is 1-15 layers, the sheet diameter is 1-5 μm, and the thickness of the sheet is 1-5 nm. The graphene sheets are staggered in the coating, and the two-dimensional structure of the graphene sheet can not only provide a conductive bridge when compounded with other materials, but also allow electromagnetic waves to experience multiple reflections and refractions between its layers, thereby enhancing reflection loss and multiple absorption loss.

[0053] The dispersant of the present invention comprises one or more of polyvinyl pyrrolidone PVP, sodium lignin sulfonate SLS, lauryl alcohol polyoxyethylene ether, polyvinyl alcohol PVA, and Disperbyk-2013.

[0054] The binder of the present invention comprises one or more of sodium carboxymethyl cellulose CMC, hydroxyethyl cellulose, methyl cellulose and ethyl cellulose.

[0055] The solvent of the present invention may be water.

[0056] The graphene electromagnetic shielding coating of the present invention does not use emulsions, such as polyurethane emulsions, acrylic emulsions, epoxy resin emulsions, etc., so as to avoid the addition of these emulsions to increase the resistivity of the coating. The graphene electromagnetic shielding coating of the present invention uses graphene as a conductive filler. After the graphene electromagnetic shielding coating is sprayed and dried, the coating thickness is generally 0.5-3μm, which is much lower than other existing electromagnetic shielding coatings: silver, copper, nickel and graphene electromagnetic shielding coatings. It has low cost, wide bandwidth, high shielding effectiveness, and can simultaneously meet the requirements of shielding materials for "thin, light, wide and high".

[0057] Second, see Figure 1 The present invention also provides a preparation method for preparing the aforementioned graphene electromagnetic shielding coating. The preparation method comprises the following steps:

[0058] Step S100, 6-10 parts of graphite powder, 0.3-2 parts of dispersant, 0.1-1 parts of binder, and 87-93.6 parts of solvent are mixed and stirred to obtain a first solution.

[0059] Step S200, emulsifying the first solution to obtain a second solution;

[0060] Step S300, homogenizing the second solution to obtain a graphene electromagnetic shielding coating.

[0061] Specifically, in step S100, the graphite powder includes one or more of ultrafine graphite powder and expanded graphite powder. The ultrafine graphite powder is obtained by grinding and crushing flake graphite, and the mesh number of the ultrafine graphite powder is greater than 3000 meshes and the purity is greater than 99%; the expanded graphite is natural flake graphite that has been acidified to form a graphite intercalation compound, which is washed with water to neutrality and dried and then rapidly heated to expand into a worm-like substance, also known as graphite worms. The mesh number of the expanded graphite powder is greater than 200 meshes, the purity is greater than 99%, and the expansion multiple is 200 times. The stirring speed is 200-500 rpm, the time is 1-2 hours, and the temperature is room temperature, thereby obtaining a graphite dispersion, i.e., the first solution.

[0062] In step S200, the emulsification speed is 20000-50000 rpm, the time is 0.2-0.5 hours, the temperature is room temperature, and the first solution is emulsified to obtain a graphene pre-dispersion liquid, that is, the second solution.

[0063] In step S300, the homogenization pressure is 100-140 MPa, the temperature is 25-80°C, and the number of times is 20-80 times. The graphene dispersion obtained after homogenizing the second solution is the graphene electromagnetic shielding coating.

[0064] The preparation method can obtain a graphene electromagnetic shielding coating with a particle size of 1-5 μm, a fineness of 0.01-3 μm, and a viscosity of 60-200 cps, solving the problems of easy sedimentation of conductive fillers, attenuation of conductive properties, and difficulty in stable dispersion of graphene. The method prepares a graphene electromagnetic shielding coating, and the coating thickness obtained after the sprayed object is cured is generally 0.5-3 μm. The electromagnetic shielding effectiveness of the coating in the 30 MHz-1.5 GHZ frequency band can reach 85-98 dB, and the volume resistivity is 0.002-0.007 Ω·cm.

[0065] The present invention will be specifically described below through specific examples. The following examples are only partial embodiments of the present invention and are not intended to limit the present invention.

[0066] Graphene electromagnetic shielding coating embodiment 1

[0067] Step S101, 6 parts of expanded graphite powder, 0.3 parts of polyvinyl pyrrolidone PVP, 0.1 parts of hydroxyethyl cellulose and 93.6 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0068] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0069] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0070] Graphene electromagnetic shielding coating embodiment 2

[0071] Step S101, 10 parts of expanded graphite powder, 0.3 parts of polyvinyl pyrrolidone PVP, 1 part of sodium carboxymethyl cellulose CMC and 88.7 parts of pure water are mixed and stirred to obtain a graphite dispersion. The expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0072] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0073] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0074] Graphene electromagnetic shielding coating embodiment 3

[0075] Step S101, 8 parts of expanded graphite powder, 1.2 parts of polyvinyl pyrrolidone PVP, 0.5 parts of sodium carboxymethyl cellulose CMC and 90.3 parts of pure water are mixed and stirred to obtain a graphite dispersion. The expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0076] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0077] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0078] Graphene electromagnetic shielding coating embodiment 4

[0079] Step S101, 9 parts of expanded graphite powder, 1 part of sodium lignin sulfonate SLS, 1 part of sodium carboxymethyl cellulose CMC and 89 parts of pure water are mixed and stirred to obtain a graphite dispersion. The expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0080] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0081] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0082] Graphene electromagnetic shielding coating embodiment 5

[0083] Step S101, 10 parts of expanded graphite powder, 2 parts of lauryl alcohol polyoxyethylene ether, 0.7 parts of hydroxyethyl cellulose and 87.3 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0084] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0085] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0086] Graphene electromagnetic shielding coating embodiment 6

[0087] Step S101, 7 parts of ultrafine graphite powder, 0.9 parts of polyvinyl pyrrolidone PVP, 0.3 parts of sodium carboxymethyl cellulose CMC and 91.8 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the mesh number of the ultrafine graphite powder is greater than 3000 meshes, the purity is greater than 99%, the stirring speed is 200 rpm, and the stirring time is 2 hours.

[0088] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0089] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0090] Graphene electromagnetic shielding coating comparative example 1

[0091] Step S101, 8 parts of graphene powder, 1.2 parts of polyvinyl pyrrolidone PVP, 0.5 parts of polyurethane emulsion and 90.3 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the stirring speed is 200 rpm and the stirring time is 2 hours.

[0092] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0093] Graphene electromagnetic shielding coating comparative example 2

[0094] Step S101, 8 parts of expanded graphite powder, 1.2 parts of polyvinyl pyrrolidone PVP, 0.5 parts of polyurethane emulsion and 90.3 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0095] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0096] Graphene electromagnetic shielding coating comparative example 3

[0097] Step S101, 8 parts of expanded graphite powder, 1.2 parts of polyvinyl pyrrolidone PVP, 0.5 parts of polyurethane emulsion and 90.3 parts of pure water are mixed and stirred to obtain a graphite dispersion, wherein the expanded graphite powder has a mesh size greater than 200 meshes, a purity greater than 99%, an expansion multiple of 200 times, a stirring speed of 200 rpm, and a stirring time of 2 hours.

[0098] Step S201, emulsifying the graphite dispersion to obtain a graphene pre-dispersion liquid, wherein the emulsification speed is 20,000 rpm and the emulsification time is 0.5 hours.

[0099] Step S301, homogenizing the graphene pre-dispersed liquid to obtain the graphene electromagnetic shielding coating of this embodiment, wherein the homogenization pressure is 140 MPa, the homogenization temperature is 40° C., and the homogenization times are 20 times.

[0100] The particle size, fineness and viscosity of graphene electromagnetic shielding coating embodiments 1-6 and graphene electromagnetic shielding coating comparative examples 1-2 were tested respectively.

[0101] A coating is obtained by applying the graphene electromagnetic shielding coating embodiments 1-6 and the graphene electromagnetic shielding coating comparison examples 1-2. The coating preparation process is as follows: cleaning the substrate; stirring the graphene electromagnetic shielding coating evenly and then applying it on the substrate with a coating thickness of 2 μm; after natural drying for 12 hours, the graphene electromagnetic shielding coating is obtained, and the electromagnetic shielding effectiveness and volume resistivity of the corresponding coating are tested.

[0102] The test results are shown in Table 1.

[0103] Table 1:

[0104]

[0105]

[0106] From Table 1 we can see that:

[0107] Compared with the particle size, fineness and viscosity of comparative examples 1-2, the particle size and fineness of embodiment 1-6 are smaller, and the viscosity can be controlled within the appropriate range of 60-200cps. Compared with the electromagnetic shielding effectiveness and volume resistivity of comparative examples 1-2, the electromagnetic shielding effectiveness of embodiment 1-6 is better and the volume resistivity is lower. The reason is that in embodiment 1-6, an appropriate proportion of expanded graphite powder or ultrafine graphite powder is selected, and a reasonable homogenization process is used to stably disperse graphene in the coating in a flaky structure, thereby reducing the particle size and fineness of the coating, avoiding the attenuation of conductive performance caused by the sedimentation of conductive fillers, and controlling the viscosity at 60-200cps, which is more convenient for subsequent spraying and brushing of the coating to form a uniform graphene electromagnetic shielding coating. Compared with Comparative Example 1, Examples 1-6 directly use graphite powder, which has the advantages of low cost. In order to obtain graphene powder, the prior art needs to first mix graphite powder, dispersant, and solvent, and then disperse, homogenize, and dry to finally form graphene powder. Therefore, the price of graphene powder is much higher than that of graphite powder. Compared with Comparative Example 2, Examples 1-6 finally obtain nanographite (i.e., graphene sheets) in the coating through the homogenization step. Comparative Example 2 removes the homogenization step, and no nanographite is formed in the final solution. Compared with Comparative Example 3, polyurethane and other emulsions are not added in Examples 1-6 to avoid the emulsion filling between the graphene sheets to affect the flow and transmission of current, thereby reducing the resistivity of the coating and being able to obtain better electromagnetic shielding effectiveness.

[0108] The above is a detailed introduction to the graphene electromagnetic shielding coating and preparation method provided in the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A graphene electromagnetic shielding coating, characterized in that: The graphene electromagnetic shielding coating is obtained by emulsifying and homogenizing a raw material composition; The raw material composition includes the following components: Graphite powder, dispersant, binder, solvent; The graphite powder includes one or more of ultrafine graphite powder and expanded graphite powder.

2. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The mass percentage of the graphite powder in the raw material composition is 6-10%; and / or The mass percentage of the dispersant in the raw material composition is 0.3-2%; and / or The mass percentage of the binder in the raw material composition is 0.1-1%.

3. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The graphene electromagnetic shielding coating comprises a graphene sheet; The number of layers of the graphene sheet is 1-15; and / or The diameter of the graphene sheet is 1-5 μm; and / or The thickness of the graphene sheet is 1-5 nm.

4. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The ultrafine graphite powder has a mesh size greater than 3000 meshes and a purity greater than 99%; and / or The mesh number of the expanded graphite powder is greater than 200 meshes, the purity is greater than 99%, and the expansion multiple is 200 times.

5. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The dispersant includes one or more of polyvinyl pyrrolidone (PVP), sodium lignin sulfonate (SLS), polyoxyethylene lauryl alcohol ether, polyvinyl alcohol (PVA), and Disperbyk-2013.

6. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The binder includes one or more of sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose, methyl cellulose, and ethyl cellulose.

7. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The solvent is water.

8. The graphene electromagnetic shielding coating according to claim 1, characterized in that: The graphene electromagnetic shielding coating has a particle size of 1-5 μm, a fineness of 0.01-3 μm, and a viscosity of 60-200 cps.

9. A method for preparing the graphene electromagnetic shielding coating according to any one of claims 1 to 8, characterized in that: The method comprises: Mixing the raw material composition to obtain a first solution; emulsifying the first solution to obtain a second solution; After the second solution is homogenized, the graphene electromagnetic shielding coating is obtained.

10. The method for preparing the graphene electromagnetic shielding coating according to claim 9, characterized in that: Mixing the raw material composition comprises: The raw material composition is stirred at a speed of 200-500 rpm for 1-2 hours at room temperature.

11. The method for preparing the graphene electromagnetic shielding coating according to claim 9, characterized in that: The emulsification speed is 20000-50000 rpm, the time is 0.2-0.5 hour, and the temperature is room temperature.

12. The method for preparing the graphene electromagnetic shielding coating according to claim 9, characterized in that: The homogenization pressure is 100-140 MPa, the temperature is 25-80° C., and the number of times is 20-80 times.

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