Aqueous graphene antistatic coating, method for its production and use

Abstract

The application relates to the field of water-based antistatic coating preparation, and discloses a water-based graphene antistatic coating, a preparation method and application thereof. The coating comprises an A component and a B component; the A component comprises modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and a filler, and the B component comprises a curing agent; wherein the modified graphene comprises graphene and amide groups grafted on the graphene; wherein, based on the total mass of the modified graphene, the nitrogen element content is 2-10 wt%, and the carbon element content is 85-97 wt%. The water-based graphene antistatic coating provided by the application has good antistatic performance and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of waterborne antistatic coating preparation, specifically to a waterborne graphene antistatic coating, its preparation method, and its application. Background Technology

[0002] Static electricity is widespread in nature. With the widespread use of polymer fabrics in daily life, static electricity generation is receiving increasing attention. People have conducted in-depth research on static electricity generation and control. Antistatic materials play an important role in the field of materials science. Antistatic coatings are the main way to eliminate static electricity on the ground in environments such as electronic factories, workshops, and laboratories. With the enrichment of application scenarios, requirements for antistatic coatings have been put forward in addition to antistatic properties, such as environmental protection, aesthetics, wear resistance, and corrosion resistance.

[0003] Currently, most antistatic floor coatings on the market incorporate conductive coated mica powder, conductive zinc oxide, conductive carbon black, carbon fiber, and carbon nanotubes as conductive media. However, the production cost of conductive mica powder and conductive zinc oxide floor coatings is relatively high, and their conductivity is prone to decay over time. Floor coatings using conductive carbon black, carbon fiber, and carbon nanotubes as conductive media have a darker color, which affects the aesthetics of the floor coating.

[0004] Graphene, a two-dimensional sheet structure with one electron layer thickness, exhibits excellent mechanical, optical, electrical, and thermal properties, with a significant advantage in electrical conductivity. Adding graphene to waterborne epoxy floor coatings can effectively improve their conductivity and mechanical properties. While considered an excellent conductive medium, graphene sheets exhibit strong van der Waals forces, making them prone to aggregation. Furthermore, the lack of abundant functional groups on the surface leads to unstable dispersion and agglomeration in various solvents. Researchers in this field have employed methods such as modifying graphene to improve its oleophilicity; however, the modified graphene still exhibits agglomeration problems in some commercially available coatings. Alternatively, graphene dispersions can be formulated using additives and added to finished coatings, but this increases VOC emissions from the coatings. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a water-based graphene antistatic coating, its preparation method, and its application. The water-based graphene antistatic coating provided by this invention has both good antistatic properties and wear resistance.

[0006] To achieve the above objectives, the first aspect of the present invention provides an aqueous graphene antistatic coating, the coating comprising component A and component B; component A comprises modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler, and component B comprises a curing agent;

[0007] The modified graphene includes graphene and amide groups grafted onto the graphene.

[0008] The modified graphene contains 2-10 wt% nitrogen and 85-97 wt% carbon, based on the total mass of the modified graphene.

[0009] A second aspect of this invention provides a method for preparing an aqueous graphene antistatic coating, the method comprising the following steps:

[0010] (1) Mix graphene with phosphoric acid solution, perform edge activation, and then perform first drying to obtain activated graphene;

[0011] (2) The activated graphene is mixed with permanganate solution and subjected to edge carboxylation reaction at a temperature not exceeding 10°C, followed by a second drying process to obtain edge carboxylated graphene.

[0012] (3) In the presence of a solvent, the edge carboxylated graphene and organic amine are contacted with a catalyst to carry out an edge amidation reaction, followed by a third drying process to obtain modified graphene.

[0013] (4) Mix component A and component B, wherein component A comprises the modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler obtained in step (3), and component B comprises a curing agent.

[0014] The third aspect of this invention provides the application of the water-based antistatic coating described in the first aspect or the water-based antistatic coating prepared by the preparation method described in the second aspect in antistatic flooring or the outer coating of oil and gas storage tank pipelines.

[0015] The beneficial effects of the present invention through the above technical solution include:

[0016] The water-based graphene antistatic coating provided by this invention has the characteristics of good antistatic performance, high adhesion, good tensile properties, and good wear resistance, which can meet the antistatic requirements of flooring, oil and gas storage tank pipelines, etc.

[0017] In the waterborne graphene antistatic coating provided by this invention, the amide groups on the modified graphene are introduced into the epoxy resin chain segments under the action of hyperbranched fatty alcohol polyether, participating in the crosslinking with the curing agent, realizing the combination of graphene and resin chain segments, constructing a three-dimensional conductive network, and enhancing the antistatic performance of the coating; the bonding force between the modified graphene and epoxy resin is improved, enhancing the wear resistance of the coating.

[0018] Existing water-based antistatic coatings contain a large amount of conductive fillers. When the conductive fillers are selected from materials such as metal powders and conductive mica, they are prone to oxidation during long-term storage, which reduces the antistatic performance of the coating and results in poor corrosion resistance. When the conductive fillers are selected from carbon-based materials (such as carbon nanotubes, graphene, carbon fibers, and carbon black), their dispersibility is poor, which also reduces the antistatic performance of the coating and affects the coating color, resulting in a black and monotonous color that fails to meet aesthetic requirements. The water-based graphene antistatic coating of this invention introduces the modified graphene provided by this invention, which facilitates the uniform dispersion of graphene in the coating, solves the problem of graphene self-agglomeration, and allows graphene to spread into a sheet-like structure in the coating, providing excellent layer overlap and abundant electronic pathways. This significantly reduces the amount of conductive filler required and solves the problems of monotonous color, poor decorative properties, and poor corrosion resistance in traditional water-based antistatic coatings. Attached Figure Description

[0019] Figure 1 These are the infrared spectra of graphene, carboxylated graphene, and modified graphene from Example 1 of this invention.

[0020] Figure 2 This is an EDS image of the modified graphene in Example 1 of the present invention;

[0021] Figure 3 This is a TEM image of the activated graphene from Example 1 of the present invention;

[0022] Figure 4 This is a TEM image of the modified graphene of Comparative Example 2 of this invention;

[0023] Figure 5 This is the EDS image of the modified graphene of Comparative Example 2 of this invention;

[0024] Figure 6 This is the EDS image of the modified graphene of Comparative Example 1 of this invention. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] The first aspect of the present invention provides an aqueous antistatic coating, the coating comprising component A and component B; component A comprises modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler, and component B comprises a curing agent;

[0027] The modified graphene includes graphene and amide groups grafted onto the graphene.

[0028] The modified graphene contains 2-10 wt% nitrogen and 85-97 wt% carbon, based on the total mass of the modified graphene.

[0029] In this invention, the presence of amide groups in the modified graphene is determined by infrared spectroscopy, which can be referred to... Figure 1 ,from Figure 1 It can be seen that modified graphene at 3270 cm⁻¹ -1 1638cm -1 1533cm -1 and 1323cm -1 The presence of characteristic peaks of the amide structure indicates that the amide group has also been grafted onto the graphene, thus achieving the modification of the graphene.

[0030] It should be noted that components A and B are stored independently.

[0031] The modified graphene of this invention has good electrical conductivity. Preferably, the conductivity of the modified graphene is ≥500 S / cm, and more preferably 500-1000 S / cm.

[0032] According to the present invention, preferably, the conductivity reduction rate of the modified graphene relative to the conductivity of graphene is ≤15%, more preferably ≤10%. Using this preferred embodiment, graphene is modified, but the impact on its conductivity is minimal, maintaining the conductive advantages of graphene materials. This indicates that the modified graphene of the present invention causes minimal damage to the graphene sheets; the modified graphene still possesses a complete sheet structure, further demonstrating that the modification of graphene occurs at its edges.

[0033] It is understood that the conductivity reduction rate = (conductivity of graphene - conductivity of modified graphene) / conductivity of graphene × 100%.

[0034] The electrical conductivity of the modified graphene described in this invention was measured using a ST-2258C multifunctional digital four-probe tester manufactured by Suzhou Crystallography Co., Ltd.

[0035] According to the present invention, preferably, the activation index of the modified graphene is ≥95%, more preferably 98-100%. This preferred embodiment demonstrates that the modified graphene of the present invention has good dispersion stability, and its application in antistatic coatings can prevent the re-agglomeration of graphene.

[0036] In this invention, the activation index of the modified graphene is used to detect and characterize the effect of surface modification of the material. Test method: Take m1 mass of modified graphene, add it to 100 ml of propylene glycol monomethyl ether, ultrasonically disperse it evenly, pour it into a 250 ml separatory funnel, and let it stand for 2 hours; remove the material that has settled at the bottom, wash it with ethanol, dry it, record the mass m2, and calculate the activation index of the modified graphene.

[0037]

[0038] According to the present invention, preferably, the median particle size of the modified graphene is 5-15 μm.

[0039] It should be noted that the particle size remains essentially unchanged throughout the entire modification process from graphene to modified graphene.

[0040] In this invention, the median particle size of the modified graphene was obtained by dynamic light scattering characterization using a Malvern Panalytical MS-3000 laser particle size analyzer. Test conditions: The sample was dispersed in deionized water at a concentration of 0.01 mg / ml, and tested after sonication for 10 minutes. The instrument's opacity was set within the range of 5-20%.

[0041] According to the present invention, preferably, the modified graphene has a layered structure, preferably 2-5 layers.

[0042] It should be noted that the layered structure remains unchanged throughout the entire modification process from graphene to modified graphene.

[0043] The layered structure of the modified graphene described in this invention was measured by TEM.

[0044] According to the present invention, the modified graphene contains nitrogen at a content of 2-10 wt%, specifically 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, and any two of these values, preferably 2-7.5 wt%; and carbon at a content of 85-97 wt%, specifically 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, and any two of these values, preferably 90-96 wt%.

[0045] According to the present invention, preferably, the modified graphene contains 1-5 wt% oxygen, based on the total mass of the modified graphene, specifically 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, and a range of any two of these values.

[0046] According to the present invention, preferably, the modified graphene contains 0.5-2 wt% hydrogen, based on the total mass of the modified graphene. Specifically, it can be 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, and a range of any two of these values.

[0047] The content of each element in the modified graphene of the present invention was quantitatively detected by an elemental analyzer (refer to T / CSTM00340-2020).

[0048] According to the present invention, preferably, in the modified graphene, amide groups are grafted onto the edges of the graphene.

[0049] In this invention, "amide groups grafted onto the edge of graphene" means that the grafting modification site is located at the edge of the graphene sheet, and the graphene sheet can retain the complete carbon structure.

[0050] The grafting positions of the amide groups in the modified graphene described in this invention were determined by EDS method, which showed that nitrogen elements were distributed at the edges of the graphene, thus proving that the amide groups were grafted at the edges of the graphene.

[0051] According to the present invention, preferably, the mass ratio of component A to component B is 2-10:1, more preferably 3-7:1.

[0052] According to the present invention, preferably, component A comprises, by weight, 0.0004-0.001 parts of modified graphene, 10-30 parts of epoxy resin, 1-3 parts of hyperbranched fatty alcohol polyether, and 20-40 parts of filler. This preferred embodiment can improve the overall performance of the coating.

[0053] In this invention, component A contains 0.0004-0.001 parts of modified graphene, specifically 0.0004 parts, 0.0005 parts, 0.0006 parts, 0.0007 parts, 0.0008 parts, 0.0009 parts, 0.001 parts, and a range of values ​​formed by any two of these points.

[0054] In this invention, component A comprises 10-30 parts of epoxy resin, specifically 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, and a range of values ​​formed by any two of these points.

[0055] In this invention, component A contains 1-3 parts of hyperbranched fatty alcohol polyether, specifically 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, and a range of values ​​composed of any two of these points.

[0056] In this invention, component A contains 20-40 parts of filler, specifically 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, and a range of values ​​formed by any two of these points.

[0057] The present invention allows for a wide range of choices of epoxy resin, which can be conventional choices in the art. Preferably, the epoxy resin is a water-based bisphenol A type epoxy resin.

[0058] More preferably, the epoxy equivalent of the waterborne bisphenol A type epoxy resin is 150-300 g / mol. eq .

[0059] According to the present invention, preferably, the weight-average molecular weight of the hyperbranched fatty alcohol polyether is 1000-10000 g / mol.

[0060] According to the present invention, preferably, the surface tension of the hyperbranched aliphatic polyether is 21-28 mN / m.

[0061] Using hyperbranched aliphatic polyethers with the above-mentioned preferred characteristics is beneficial to the bonding between amide groups and epoxy segments on modified graphene, thereby improving the antistatic properties, tensile properties, and wear resistance of the coating.

[0062] The present invention allows for a wide range of choices for the filler, which can be conventional choices in the field, and can be appropriately selected according to actual needs. Preferably, the filler is selected from at least one of aluminum tripolyphosphate, barium sulfate, titanium dioxide, calcium carbonate, flake glass, bentonite, talc, zinc oxide, mica powder, and mica iron oxide.

[0063] The present invention allows for a wide range of choices for the type of curing agent, which can be conventional choices in the art. Preferably, the curing agent is a water-based polyamide curing agent.

[0064] More preferably, the active hydrogen equivalent of the waterborne polyamide curing agent is 210-260 g / mol.

[0065] According to the present invention, preferably, component A further comprises an additive, which includes at least one selected from leveling agents, defoamers, and dispersants. The above-mentioned additives are common additives used in coatings in the art, and the selection and dosage of the above-mentioned additives can be appropriately chosen according to actual needs. For example, the leveling agent can be selected from silicone leveling agents, polyether siloxane leveling agents, and acrylate leveling agents, etc.; the defoamer can be silicone defoamers, polymeric defoamers, etc.; the dispersant can be selected from fatty acid epoxy dispersants, polypolyol dispersants, and polyethyleneimine dispersants, etc.

[0066] Preferably, component A contains 0.5-5 parts by weight of an additive.

[0067] According to the present invention, preferably, component A further comprises a thickener. The thickener described in this invention can be a conventional choice in the art. This invention exemplarily uses a polyurethane thickener.

[0068] The present invention does not impose a particular limitation on the amount of thickener used, as long as it is sufficient to achieve the purpose of adjusting viscosity, and can be appropriately selected according to actual needs. Preferably, component A contains 2-8 parts by weight of thickener.

[0069] Preferably, component A further comprises a co-solvent. The co-solvent described in this invention can be a conventional choice in the art. Preferably, the co-solvent is selected from at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, and diethylene glycol butyl ether.

[0070] According to the present invention, preferably, component A contains 5-20 parts by weight of a cosolvent.

[0071] According to the present invention, preferably, component A further comprises water.

[0072] According to the present invention, preferably, component A contains 10-30 parts by weight of water.

[0073] A second aspect of this invention provides a method for preparing a water-based antistatic coating, the method comprising the following steps:

[0074] (1) Mix graphene with phosphoric acid solution, perform edge activation, and then perform first drying to obtain activated graphene;

[0075] (2) The activated graphene is mixed with permanganate solution and subjected to edge carboxylation reaction at a temperature not exceeding 10°C, followed by a second drying process to obtain edge carboxylated graphene.

[0076] (3) In the presence of a solvent, the edge carboxylated graphene and organic amine are contacted with a catalyst to carry out an edge amidation reaction, followed by a third drying process to obtain modified graphene.

[0077] (4) Mix component A and component B, wherein component A comprises the modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler obtained in step (3), and component B comprises a curing agent.

[0078] According to the present invention, preferably, the median particle size of the graphene is 5-15 μm.

[0079] The graphene raw material used in this invention has high purity. Preferably, the carbon content in the graphene is ≥99% by mass.

[0080] The graphene raw material used in this invention has high electrical conductivity. Preferably, the electrical conductivity of the graphene is ≥600 S / cm, and more preferably 600-1200 S / cm.

[0081] According to the present invention, preferably, the graphene has a layered structure, preferably 2-5 layers. This type of graphene has the advantage of good electrical conductivity, and is easy to activate and modify functional groups at the graphene edges, while also having a price advantage.

[0082] The graphene raw material described in this invention can also be obtained commercially or by conventional methods, as long as the graphene raw material with the above characteristics can be obtained.

[0083] In step (1) of this invention, phosphate groups are used to activate the defects at the edge of the graphene sheets, thereby increasing the activity of the carbon atoms at the edge.

[0084] According to the present invention, preferably, the edge activation in step (1) is performed under ultrasound conditions.

[0085] According to the present invention, preferably, the conditions for edge activation in step (1) include: ultrasonic power of 300-1500W, preferably 300-900W; and ultrasonic treatment time of 0.5-5h.

[0086] According to the present invention, preferably, the mass ratio of graphene to phosphoric acid is 1:0.5-5, specifically 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, and any two of these values ​​within a range, preferably 1:1-3. This preferred embodiment is more conducive to improving the activity of carbon atoms at the edges.

[0087] According to the present invention, preferably, the mass concentration of the phosphoric acid solution is 1-10%.

[0088] The present invention does not have any particular limitation on the first drying in step (1), and it can be carried out with reference to conventional methods in the art. Preferably, the first drying in step (1) is vacuum drying.

[0089] Preferably, the method further includes: before the edge activation product of step (1) is first dried, solid-liquid separation and washing are performed sequentially.

[0090] The present invention does not impose any particular limitation on the method of solid-liquid separation, and it can be achieved using conventional techniques in the field.

[0091] The present invention does not specify any particular conditions for the washing process, and can be carried out by referring to conventional methods in the art.

[0092] In step (2) of this invention, carboxyl functional groups are grafted onto the edges under mild reaction conditions without affecting the integrity of the graphene sheet structure.

[0093] According to the present invention, the temperature of the edge carboxylation reaction in step (2) is not higher than 10°C, preferably 0-10°C, specifically 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, and any two of these values ​​forming a range. By employing this preferred embodiment, using permanganate to carboxylate the graphene edges at low temperatures not only effectively avoids damage to the graphene sheet structure during carboxylation, thus preventing a decrease in the graphene's conductivity, but also provides active sites for subsequent amidation grafting modification of the graphene.

[0094] According to the present invention, preferably, the conditions for the edge carboxylation reaction in step (2) include: a temperature of 0-10°C and a time of 1-5 h.

[0095] Preferably, the edge carboxylation reaction in step (2) is carried out under stirring conditions. The present invention does not impose any particular limitation on the stirring conditions, which can be appropriately selected according to actual circumstances.

[0096] In step (2) of this invention, the edge carboxylation reaction is terminated by adding a terminator. This invention allows for a wide range of terminators; in this embodiment, hydrogen peroxide is used as an example terminator.

[0097] The present invention does not have a particular limitation on the amount of the terminator, as long as it achieves the purpose of terminating the reaction.

[0098] For safety reasons, the edge carboxylation reaction in step (2) of this invention is diluted with water before the terminating agent is added.

[0099] According to the present invention, preferably, the mass ratio of activated graphene to permanganate solution is 0.03-0.5:1, specifically 0.03:1, 0.05:1, 0.08:1, 0.1:1, 0.13:1, 0.15:1, 0.18:1, 0.2:1, 0.23:1, 0.25:1, 0.28:1, 0.3:1, 0.33:1, 0.35:1, 0.38:1, 0.4:1, 0.43:1, 0.45:1, 0.48:1, 0.5:1, and the range of any two of these values, preferably 0.05-0.3:1.

[0100] According to the present invention, preferably, the permanganate solution comprises potassium permanganate and concentrated sulfuric acid.

[0101] According to the present invention, preferably, the mass ratio of concentrated sulfuric acid to potassium permanganate is 5-10:1.

[0102] According to the present invention, preferably, the method for preparing the permanganate solution includes mixing potassium permanganate and concentrated sulfuric acid at a temperature below 10°C, preferably 0-10°C. During the mixing process, conventional methods such as stirring and / or ultrasound can be used to accelerate uniform mixing.

[0103] The present invention does not have any particular limitation on the second drying step (2), and it can be carried out with reference to conventional methods in the art. Preferably, the second drying step (2) is freeze drying.

[0104] The present invention does not specifically limit the conditions for the edge amidation reaction, and can refer to conventional methods in the art. Preferably, the conditions for the edge amidation reaction in step (3) include: a temperature of 60-120°C and a time of 2-6 hours.

[0105] According to the present invention, preferably, the mass ratio of organic amine to edge carboxyl graphene is 0.5-8:1, more preferably 1-5:1.

[0106] According to the present invention, preferably, the mass ratio of the catalyst to the edge carboxylated graphene is 0.03-0.3:1, more preferably 0.08-0.25:1.

[0107] The present invention does not impose any particular limitation on the order of adding the solvent, edge-carboxylated graphene, organic amine, and catalyst in step (3). They can be added separately or together. In a preferred embodiment of the present invention, the solvent is first mixed with the edge-carboxylated graphene, then the catalyst is added, and finally the organic amine is added.

[0108] According to a specific embodiment of the present invention, in step (3), the solvent is first mixed with edge carboxylated graphene, then a catalyst is added and stirred for 0.5-5 hours, and finally an organic amine is added to carry out an edge amidation reaction.

[0109] The present invention does not particularly limit the type of organic amine, and it can be any organic amine commonly found in the art. Preferably, the organic amine is selected from at least one of triethylenetetramine, n-butylamine, hexamethylenediamine, dipropylamine, ethylenediamine, tetraethylenepentamine, and diethylenetriamine;

[0110] The present invention does not particularly limit the type of catalyst, and any conventional choice in the art can be used. Preferably, the catalyst is selected from at least one of methyl orthosilicate, diphenylsilane, carbodiimide, urea cationic / quaternary phosphine salt, benzotriazole, borane, and hydrocarbon-substituted borane.

[0111] The present invention does not particularly limit the type of solvent, and any conventional choice in the art can be used. In an exemplary embodiment of the present invention, N,N-dimethylformamide (DMF) is used as the solvent.

[0112] The present invention does not have a particular limitation on the amount of solvent used, but the amount is determined by the ability of other substances to be uniformly dispersed.

[0113] The present invention does not have any particular limitation on the third drying step (3), and it can be carried out with reference to conventional methods in the art. Preferably, the third drying step (3) is freeze drying.

[0114] The method further includes washing the edge amidation reaction product described in step (3) before subjecting it to a third drying.

[0115] The present invention does not impose any particular limitation on the washing conditions, and can be carried out with reference to conventional methods in the art.

[0116] According to the present invention, preferably, the mass ratio of component A to component B is 2-10:1, more preferably 3-7:1.

[0117] According to the present invention, preferably, component A comprises, by weight, 0.0004-0.001 parts of modified graphene, 10-30 parts of epoxy resin, 1-3 parts of hyperbranched fatty alcohol polyether, and 20-40 parts of filler.

[0118] The present invention allows for a wide range of choices of epoxy resin, which can be conventional choices in the art. Preferably, the epoxy resin is a water-based bisphenol A type epoxy resin.

[0119] More preferably, the epoxy equivalent of the waterborne bisphenol A type epoxy resin is 150-300 g / mol. eq .

[0120] According to the present invention, preferably, the weight-average molecular weight of the hyperbranched fatty alcohol polyether is 1000-10000 g / mol.

[0121] According to the present invention, preferably, the surface tension of the hyperbranched aliphatic polyether is 21-28 mN / m.

[0122] The present invention allows for a wide range of choices for the filler, which can be conventional choices in the field, and can be appropriately selected according to actual needs. Preferably, the filler is selected from at least one of aluminum tripolyphosphate, barium sulfate, titanium dioxide, calcium carbonate, flake glass, bentonite, talc, zinc oxide, mica powder, and mica iron oxide.

[0123] The present invention allows for a wide range of choices for the type of curing agent, which can be conventional choices in the art. Preferably, the curing agent is a water-based polyamide curing agent.

[0124] More preferably, the active hydrogen equivalent of the waterborne polyamide curing agent is 210-260 g / mol.

[0125] According to the present invention, preferably, component A further comprises an auxiliary agent, which includes at least one selected from leveling agents, defoamers, and dispersants. The specific types and amounts of the auxiliary agents are the same as in the first aspect, and will not be detailed here.

[0126] According to the present invention, preferably, component A further comprises a thickener. The thickener described in this invention can be a conventional choice in the art. This invention exemplarily uses a polyurethane thickener.

[0127] The present invention does not impose a particular limitation on the amount of thickener used, as long as it is sufficient to achieve the purpose of adjusting viscosity, and can be appropriately selected according to actual needs. Preferably, component A contains 2-8 parts by weight of thickener.

[0128] Preferably, component A further comprises a co-solvent. The co-solvent described in this invention can be a conventional choice in the art. Preferably, the co-solvent is selected from at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, and diethylene glycol butyl ether.

[0129] According to the present invention, preferably, component A contains 5-20 parts by weight of a cosolvent.

[0130] According to the present invention, preferably, component A further comprises water.

[0131] According to the present invention, preferably, component A contains 10-30 parts by weight of water.

[0132] The present invention does not have any particular limitation on the mixing process described in step (4), and can be carried out with reference to conventional methods in the art. Preferably, the preparation process of component A in step (4) includes: dispersing the modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler obtained in step (3).

[0133] The dispersion described in this invention can be performed using methods conventional in the art. Preferably, the dispersion is carried out in a high-speed shearing machine, and the dispersion conditions preferably include: a rotation speed of 800-1500 rpm, more preferably 1200-1500 rpm; and a dispersion time of 10-60 min, more preferably 30-60 min.

[0134] According to a specific embodiment of the present invention, the preparation process of component A in step (4) includes: first dispersion of cosolvent, water, epoxy resin, additive and hyperbranched fatty alcohol polyether, then addition of modified graphene and filler obtained in step (3) for second dispersion to obtain dispersed material; and adding thickener to the dispersed material.

[0135] Preferably, the method further includes: first grinding the dispersed material to D... 50 ≤25μm, then add thickener.

[0136] In this invention, the terms "first," "second," and "third" do not limit the substances and operations, but are only used to distinguish the substances introduced in different steps and the operations performed in different stages.

[0137] The third aspect of this invention provides the application of the water-based antistatic coating described in the first aspect or the water-based antistatic coating prepared by the preparation method described in the second aspect in antistatic floor coating or the outer coating of oil and gas storage tank pipelines.

[0138] The water-based antistatic coating described in this invention is suitable for antistatic flooring applications, such as in electronics, aviation, medical equipment, printing, and organic solvent factories that require antistatic flooring. It can be applied to a substrate.

[0139] The present invention will be described in detail below through embodiments.

[0140] In the following examples and test cases, room temperature refers to 25°C;

[0141] In the following embodiments, scanning electron microscopy (SEM) was used to characterize the material morphology. Specifically, the instrument used was a ZEISS-MERLIN high-resolution field emission scanning electron microscope from Germany. The test conditions were as follows: the sample was directly pressed onto the sample stage containing conductive tape, and then inserted into the electron microscope for observation; the accelerating voltage was 3kV, the current was 30pA, the magnification was 500-5000x, and the sample could be switched to Mapping mode for EDS analysis.

[0142] The electrical conductivity parameters of the powder were tested using a ST-2258C multifunctional digital four-probe tester manufactured by Suzhou Jingge Co., Ltd.

[0143] The median particle size was obtained through dynamic light scattering characterization using a Malvern Panalytical MS-3000 laser particle size analyzer. Test conditions: Samples were dispersed in deionized water at a concentration of 0.01 mg / ml, and tested after sonication for 10 min. The instrument's opacity was set between 5% and 20%.

[0144] Example 1

[0145] Step 1, weigh 20g of graphene powder (D 50 =10μm, conductivity 800S / cm, carbon mass content 99.5%, 4 layers), added to 1000g of 5wt% phosphoric acid solution, ultrasonically treated with 600W for 1h, then filtered, washed with deionized water until neutral, and vacuum dried at 60℃ to obtain edge-activated graphene.

[0146] Step 2: Weigh 180g of concentrated sulfuric acid and place it in a 4℃ low-temperature water bath. Slowly add 20g of potassium permanganate and stir slowly until the potassium permanganate is completely dissolved. Then add 20g of edge-activated graphene powder and maintain the temperature at 4℃. React for 2 hours with stirring. Dilute with 1000g of deionized water and add 10g of hydrogen peroxide to terminate the reaction. Then filter, wash with deionized water until neutral, and freeze dry to obtain carboxylated graphene powder.

[0147] Step 3: Weigh 10g of carboxylated graphene powder and add it to DMF solution to prepare a dispersion with a concentration of 1mg / mL. Add 2g of borane and stir at room temperature for 1h. Then add 30g of triethylenetetramine and react at 80℃ for 3h. Wash with deionized water until neutral and freeze-dry to obtain modified graphene powder. The composition and parameter characteristics are shown in Table 1.

[0148] Step 4: Weigh 15g of propylene glycol monomethyl ether and 20g of deionized water, then add 25g of waterborne bisphenol A epoxy resin (CYDW-100, 220g / mol), 2g of dispersant BYK310, 0.3g of defoamer TEGO810, 0.8g of leveling agent BYK180, and 1.5g of hyperbranched fatty alcohol polyether (TEGO W111, 6500g / mol, 25mN / m). Stir until homogeneous, then add 0.0008g of modified graphene obtained in Step 3, 3g of aluminum tripolyphosphate, 10g of titanium dioxide, 4g of flake glass, and 14g of bentonite. Disperse the mixture using high-speed shearing at 1300r / min and stir for 30min to obtain a mixture. Place the obtained mixture in a sand mill and grind it at 2000r / min until the particle size D of the slurry is reached. 50 The thickness is 20 μm. Then, it is mixed with 5 g of polyurethane thickener (Yoshida F0410, 1200 cps) at a stirring speed of 1000 rpm for 40 min to obtain component A. Component A is then mixed with component B (curing agent EH659w, active hydrogen equivalent 215 g / mol) at a mass ratio of 5:1 to obtain waterborne graphene antistatic coating.

[0149] The infrared spectrum of the modified graphene in Example 1 is given as an example. Figure 1 As shown. From Figure 1 It can be seen that graphene is found in the 3450-3700 cm⁻¹ range. -1 A weak stretching vibration peak of OH bonds appeared at 3670 cm⁻¹, which may be due to a small amount of water or other impurities containing OH on the graphene surface. Carboxylated graphene showed a peak at 3670 cm⁻¹. -1 The stretching vibration peak of the OH bond appears at 1560-1760 cm⁻¹. -1 The stretching vibration peak of the C=O bond appearing at 1200 cm⁻¹ is generated by the carboxyl functional group, while the peak at 1200 cm⁻¹ is generated by the carboxyl functional group. -1 and 1410cm -1 The peaks appearing on the left and right are due to the bending vibration of the OH bond and the stretching vibration of the CO bond, respectively, indicating that the carboxylation function of graphene has been achieved. Modified graphene at 3270 cm⁻¹ -1 1638cm -1 1533cm -1 and 1323cm -1 The presence of characteristic peaks of the amide structure indicates that the amide group has been grafted onto the graphene, thus achieving the modification of the graphene.

[0150] An exemplary EDS image of the modified graphene in Example 1 is provided, such as... Figure 2 As shown. From Figure 2It can be seen that the graphene sheets maintain a complete carbon structure, with oxygen and nitrogen elements only present at the edges. This indicates that, through control, the modification of graphene mainly occurs at the edges of the graphene sheets, with minimal damage to the graphene sheets, thus preserving the structural integrity of the graphene.

[0151] An exemplary TEM image of the activated graphene from Example 1 is provided, such as... Figure 3 As shown. From Figure 3 As can be seen, after activation, the edges of graphene are opened up, exhibiting a loose structure, which is conducive to the subsequent carboxylation reaction.

[0152] Example 2

[0153] Step 1, weigh 20g of graphene powder (D 50 =15μm, conductivity 1200S / cm, carbon mass content 99.9%, 2 layers), added to 1300g of 2wt% phosphoric acid solution, ultrasonically treated with 400W power for 0.5h, then filtered, washed with deionized water, and vacuum dried at 60℃ to obtain edge-activated graphene.

[0154] Step 2: Weigh 90g of concentrated sulfuric acid and place it in a 1℃ low-temperature water bath. Slowly add 15g of potassium permanganate and stir slowly until the potassium permanganate is completely dissolved. Then add 20g of edge-activated graphene powder and maintain the temperature at 1℃. React for 5 hours with stirring. Dilute with 500g of deionized water and add 8g of hydrogen peroxide to terminate the reaction. Then filter, wash with deionized water until neutral, and freeze dry to obtain carboxylated graphene powder.

[0155] Step 3: Weigh 10g of carboxylated graphene powder and add it to DMF solution to prepare a dispersion with a concentration of 1mg / mL. Add 1g of diphenylsilane and stir at room temperature for 1h. Then add 20g of triethylenetetramine and react at 60℃ for 5h. Wash with deionized water until neutral and freeze-dry to obtain modified graphene powder. The composition and parameter characteristics are shown in Table 1.

[0156] Step 4: Weigh 20g of ethylene glycol monobutyl ether and 28g of deionized water, then add 20g of waterborne bisphenol A epoxy resin (CYDW-100, 220g / mol), 1.3g of dispersant BYK310, 0.3g of defoamer TEGO810, 0.7g of leveling agent BYK180, and 1g of hyperbranched fatty alcohol polyether (TEGO W111, 6500g / mol, 25mN / m). Stir until homogeneous, then add 0.0004g of modified graphene obtained in Step 3, 2g of aluminum tripolyphosphate, 8g of titanium dioxide, 3g of flake glass, and 11g of bentonite. Disperse using high-speed shear at 1300r / min and stir for 30min to obtain a mixture. Place the obtained mixture in a sand mill at 2000r / min and grind until the particle size D of the slurry is reached. 50 The thickness is 20 μm. Then, it is mixed with 8 g of polyurethane thickener (Yoshida F0410, 1200 cps) at a stirring speed of 1000 rpm for 40 min to obtain component A. Component A is then mixed with component B (curing agent EH659w, active hydrogen equivalent 215 g / mol) at a mass ratio of 6:1 to obtain waterborne graphene antistatic coating.

[0157] Example 3

[0158] Step 1, weigh 20g of graphene powder (D 50 =5μm, conductivity 650S / cm, carbon mass content 99.2%, 5 layers), added to 700g of 8wt% phosphoric acid solution, ultrasonically treated with 800W power for 4h, then filtered, washed with deionized water, and vacuum dried at 60℃ to obtain edge-activated graphene.

[0159] Step 2: Weigh 125g of concentrated sulfuric acid and place it in a 5℃ low-temperature water bath. Slowly add 25g of potassium permanganate and stir slowly until the potassium permanganate is completely dissolved. Then add 20g of edge-activated graphene powder and maintain the temperature at 5℃. React for 1.5h with stirring. Dilute with 700g of deionized water and add 15g of hydrogen peroxide to terminate the reaction. Then filter, wash with deionized water until neutral, and freeze dry to obtain carboxylated graphene powder.

[0160] Step 3: Weigh 10g of carboxylated graphene powder and add it to DMF solution to prepare a dispersion with a concentration of 1mg / mL. Add 2.3g of methyl orthosilicate and stir at room temperature for 1h. Then add 35g of hexamethylenediamine and react at 100℃ for 2h. Then wash with deionized water until neutral and freeze-dry to obtain modified graphene powder. The composition and parameter characteristics are shown in Table 1.

[0161] Step 4: Weigh 10g of diethylene glycol butyl ether and 18g of deionized water, then add 28g of waterborne bisphenol A epoxy resin (STE600H, 650), 2.5g of dispersant BYK310, 0.6g of defoamer TEGO810, 0.9g of leveling agent BYK180, and 2.5g of hyperbranched fatty alcohol polyether (BYK1640, 3200g / mol, 23mN / m). Stir until homogeneous, then add 0.001g of modified graphene obtained in Step 3, 5g of aluminum tripolyphosphate, 18g of titanium dioxide, 5g of flake glass, and 7g of bentonite. Disperse the mixture using high-speed shearing at 1300r / min and stir for 30min to obtain a mixture. Place the mixture in a sand mill and grind it at 2000r / min until the particle size D of the slurry is reached. 50 The thickness is 20 μm. Then, it is mixed with 3 g of polyurethane thickener (Yoshida F0410, 1200 cps) at a stirring speed of 1000 rpm for 40 min to obtain component A. Component A is then mixed with component B (curing agent EH659w, active hydrogen equivalent 215 g / mol) at a mass ratio of 3:1 to obtain waterborne graphene antistatic coating.

[0162] Example 4

[0163] The procedure was carried out according to Example 1, except that in step 1, 1600 g of a 5 wt% phosphoric acid solution was used. The results are shown in Table 1.

[0164] Comparative Example 1

[0165] The procedure was carried out according to Example 1, except that the reaction temperature in step 2 was 20°C. The results are shown in Table 1.

[0166] An example is given: the EDS diagram of the modified graphene in Comparative Example 1, such as... Figure 6 As shown. From Figure 6 It can be seen that the graphene sheets are completely carboxylated and amidated.

[0167] Comparative Example 2

[0168] The procedure was performed according to Example 1, except that step 1 was omitted. The results are shown in Table 1.

[0169] Examples include TEM images of the modified graphene in Comparative Example 2, such as... Figure 4 As shown. From Figure 4 It can be seen that without activation treatment, the edges of graphene still have a dense layered structure, which is not conducive to subsequent carboxylation modification.

[0170] An example is given: the EDS diagram of the modified graphene in Comparative Example 2, such as... Figure 5 As shown. From Figure 5It can be seen that in the modified graphene obtained without activation treatment, the modifying elements are not only distributed on the surface of the graphene, but are also uniformly and loosely distributed on the graphene, indicating that uniform weak modification has been performed on the graphene, and the effect is poor.

[0171] Comparative Example 3

[0172] The procedure was carried out according to Example 1, except that hyperbranched fatty alcohol polyether was not added in step 4.

[0173] Table 1

[0174]

[0175] Note: A refers to the rate of decrease in conductivity of the modified graphene relative to the conductivity of graphene.

[0176] Test Example 1

[0177] The waterborne graphene antistatic coatings prepared in the examples and comparative examples were tested according to SJ / T11294-2018 "General Specification for Antistatic Floor Coatings" for their tensile bond strength (under standard conditions), impact resistance (with a 1000g steel ball), abrasion resistance, and antistatic properties (point-to-point resistance).

[0178] Table 2

[0179]

[0180] As can be seen from the results in Table 2, the waterborne graphene antistatic coating provided by the present invention has a lower surface resistivity, which indicates that the waterborne graphene antistatic coating of the present invention has better antistatic performance.

[0181] Moreover, the water-based graphene antistatic coating provided by this invention has better adhesion, better tensile properties, and better wear resistance.

[0182] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A water-based graphene antistatic coating, characterized in that, The coating comprises component A and component B; component A contains modified graphene, epoxy resin, hyperbranched fatty alcohol polyether, and filler, and component B contains a curing agent; The modified graphene includes graphene and amide groups grafted onto the graphene. The modified graphene contains 2-10 wt% nitrogen and 85-97 wt% carbon, based on the total mass of the modified graphene.

2. The coating according to claim 1, wherein, The modified graphene has an electrical conductivity ≥500 S / cm, preferably 500-1000 S / cm; Preferably, the conductivity reduction rate of the modified graphene is ≤15% relative to the conductivity of graphene, and more preferably ≤10%. Preferably, the activation index of the modified graphene is ≥95%, and more preferably 98-100%. Preferably, the median particle size of the modified graphene is 5-15 μm; Preferably, the modified graphene has a layered structure, preferably 2-5 layers.

3. The coating according to claim 1 or 2, wherein, In the modified graphene, based on the total mass of the modified graphene, the nitrogen content is 2-7.5 wt% and the carbon content is 90-96 wt%. Preferably, the modified graphene contains 1-5 wt% oxygen, based on the total mass of the modified graphene. Preferably, the modified graphene contains 0.5-2 wt% hydrogen, based on the total mass of the modified graphene. Preferably, in the modified graphene, amide groups are grafted onto the edges of the graphene.

4. The coating according to any one of claims 1-3, wherein, The mass ratio of component A to component B is 2-10:1, preferably 3-7:1; Preferably, component A, by weight, comprises 0.0004-0.001 parts of modified graphene, 10-30 parts of epoxy resin, 1-3 parts of hyperbranched fatty alcohol polyether, and 20-40 parts of filler.

5. The coating according to any one of claims 1-4, wherein, The epoxy resin is a waterborne bisphenol A type epoxy resin, and the epoxy equivalent of the waterborne bisphenol A type epoxy resin is preferably 150-300 g / mol. eq ; Preferably, the weight-average molecular weight of the hyperbranched fatty alcohol polyether is 1000-10000 g / mol; Preferably, the surface tension of the hyperbranched aliphatic polyether is 21-28 mN / m; Preferably, the filler is selected from at least one of aluminum tripolyphosphate, barium sulfate, titanium dioxide, calcium carbonate, flake glass, bentonite, talc, zinc oxide, mica powder, and mica iron oxide; Preferably, the curing agent is a water-based polyamide curing agent, and the active hydrogen equivalent of the water-based polyamide curing agent is preferably 210-260 g / mol.

6. The coating according to any one of claims 1-5, wherein, Component A further includes a thickener, preferably a polyurethane thickener; Preferably, component A contains 2-8 parts by weight of thickener; Preferably, component A further comprises a co-solvent, which is preferably selected from at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, and diethylene glycol butyl ether; Preferably, component A contains 5-20 parts by weight of a cosolvent; Preferably, component A further comprises water; Preferably, component A contains 10-30 parts by weight of water.

7. A method for preparing an aqueous graphene antistatic coating, characterized in that, The method includes the following steps: (1) Mix graphene with phosphoric acid solution, perform edge activation, and then perform first drying to obtain activated graphene; (2) The activated graphene is mixed with permanganate solution and subjected to edge carboxylation reaction at a temperature not exceeding 10°C, followed by a second drying process to obtain edge carboxylated graphene. (3) In the presence of a solvent, the edge carboxylated graphene and organic amine are contacted with a catalyst to carry out an edge amidation reaction, followed by a third drying process to obtain modified graphene. (4) Mix component A and component B, wherein component A comprises the modified graphene, epoxy resin, hyperbranched fatty alcohol polyether and filler obtained in step (3), and component B comprises a curing agent.

8. The preparation method according to claim 7, wherein, The median particle size of the graphene is 5-15 μm; Preferably, the graphene contains ≥99% carbon by mass; Preferably, the electrical conductivity of the graphene is ≥600 S / cm, and more preferably 600-1200 S / cm; Preferably, the graphene has a layered structure, preferably 2-5 layers.

9. The preparation method according to claim 7 or 8, wherein, The edge activation described in step (1) is performed under ultrasound conditions; Preferably, the conditions for edge activation in step (1) include: ultrasonic power of 300-1500W, preferably 300-900W; and ultrasonic treatment time of 0.5-5h. Preferably, the mass ratio of graphene to phosphoric acid is 1:0.5-5, and more preferably 1:1-3.

10. The preparation method according to any one of claims 7-9, wherein, The conditions for the edge carboxylation reaction in step (2) include: a temperature of 0-10℃ and a time of 1-5h; Preferably, the mass ratio of activated graphene to permanganate solution is 0.03-0.5:1, more preferably 0.05-0.3:1; Preferably, the permanganate solution comprises potassium permanganate and concentrated sulfuric acid; Preferably, the mass ratio of concentrated sulfuric acid to potassium permanganate is 5-10:1; Preferably, the method for preparing the permanganate solution includes mixing potassium permanganate and concentrated sulfuric acid at a temperature below 10°C.

11. The preparation method according to any one of claims 7-10, wherein, The conditions for the edge amidation reaction in step (3) include: a temperature of 60-120℃ and a time of 2-6h; Preferably, the mass ratio of organic amine to edge-carboxylated graphene is 0.5-8:1, more preferably 1-5:1; Preferably, the mass ratio of the catalyst to the edge-carboxylated graphene is 0.03-0.3:1, more preferably 0.08-0.25:1; Preferably, the organic amine is selected from at least one of triethylenetetramine, n-butylamine, hexamethylenediamine, dipropylamine, ethylenediamine, tetraethylenepentamine, and diethylenetriamine; Preferably, the catalyst is selected from at least one of methyl orthosilicate, diphenylsilane, carbodiimide, urea cationic / quaternary phosphine salt, benzotriazole, borane, and hydrocarbon-substituted borane.

12. The preparation method according to any one of claims 7-11, wherein, The mass ratio of component A to component B is 2-10:1, preferably 3-7:1; Preferably, component A, by weight, comprises 0.0004-0.001 parts of modified graphene, 10-30 parts of epoxy resin, 1-3 parts of hyperbranched fatty alcohol polyether, and 20-40 parts of filler.

13. The preparation method according to any one of claims 7-12, wherein, The epoxy resin is a waterborne bisphenol A type epoxy resin, and the epoxy equivalent of the waterborne bisphenol A type epoxy resin is preferably 150-300 / mol. eq ; Preferably, the weight-average molecular weight of the hyperbranched fatty alcohol polyether is 1000-10000 g / mol; Preferably, the surface tension of the hyperbranched aliphatic polyether is 21-28 mN / m; Preferably, the filler is selected from at least one of aluminum tripolyphosphate, barium sulfate, titanium dioxide, calcium carbonate, flake glass, bentonite, talc, zinc oxide, mica powder, and mica iron oxide; Preferably, the curing agent is a water-based polyamide curing agent, and the active hydrogen equivalent of the water-based polyamide curing agent is preferably 210-260 g / mol.

14. The preparation method according to any one of claims 7-13, wherein, Component A further includes a thickener, preferably a polyurethane thickener; Preferably, component A contains 2-8 parts by weight of thickener; Preferably, component A further comprises a co-solvent, which is preferably selected from at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, and diethylene glycol butyl ether; Preferably, component A contains 5-20 parts by weight of a cosolvent; Preferably, component A further comprises water; Preferably, component A contains 10-30 parts by weight of water.

15. The application of a waterborne antistatic coating according to any one of claims 1-6 or a waterborne antistatic coating prepared by any one of claims 7-14 in antistatic flooring or the outer coating of oil and gas storage tank pipelines.

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