A graphene-based waterborne radiation-cured coating, coating method, metal-based bipolar plate and proton exchange membrane fuel cell

Abstract

The present application relates to a kind of graphene-based waterborne radiation-cured coating, coating method, metal-based bipolar plate and proton exchange membrane fuel cell, coating ingredients include graphene derivative, waterborne radiation-cured resin, graphene derivative is obtained by graphene oxidation modification, graphene derivative is stably dispersed in waterborne radiation-cured resin, the conductivity of graphene derivative is greater than 200S / cm.The coating is applied to the surface of metal-based bipolar plate by any one method of bar coating method, blade coating method, roll coating method and spraying method, and a graphene-based waterborne radiation-cured coating is formed by stage curing.The present application uses graphene as the main component, uses more environmentally friendly waterborne radiation-cured resin as the organic binder component in coating, brings corrosion protection effect to metal-based bipolar plate while ensuring conductivity, does not add heavy metal ions in coating, and does not use volatile organic solvents, safe and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a graphene-based waterborne radiation-curing coating, a coating method, a metal-based bipolar plate, and a proton exchange membrane fuel cell. Background Technology

[0002] The overuse of fossil fuels in modern industrial society has led to serious environmental problems. With the increasing global demand for clean and sustainable energy applications, proton exchange membrane fuel cell (PEMFC) technology has experienced rapid growth and development. PEMFCs, with their advantages of high efficiency, cleanliness, and rapid refueling, have become the most promising solution in the fuel cell field.

[0003] Bipolar plates are key components of PEMFC stacks, playing a crucial role in supporting membrane electrode assembly, current collection, gaseous reactant transport, and thermal and water management. For these functions, a good bipolar plate material needs to possess reliable mechanical strength, high electrical and thermal conductivity, low permeability, and good hydrophobicity. Compared to graphene bipolar plates, metal-based bipolar plates offer advantages such as superior mechanical properties, smaller size, and ease of processing. Stainless steel or titanium alloy bipolar plates have attracted widespread attention due to their excellent corrosion resistance. However, in PEMFCs, bipolar plates operate in a high-temperature, acidic environment of 68-80°C and a pH of approximately 3, making even stainless steel or titanium alloy bipolar plates susceptible to corrosion.

[0004] Therefore, corrosion-resistant conductive coatings on the surface of metal-based bipolar plates are currently the main solution to the above problems. Existing methods generally involve preparing the coating on the surface of the metal-based bipolar plate through vacuum deposition. The coating materials include amorphous carbon, precious metals, and conductive ceramics. Vacuum deposition includes vacuum deposition methods such as physical vapor deposition and chemical vapor deposition. However, the existing deposition methods have low production efficiency, high material costs, and are not easy to carry out efficient roll-to-roll production.

[0005] Graphene is a two-dimensional material only one atom thick, possessing excellent physicochemical properties. For example, graphene has a thermal conductivity of up to 5300 W / (m·K), a carrier mobility exceeding 15000 cm² / (V·s) at room temperature, and a strength of up to 1.0 TPa. It also exhibits excellent physical barrier properties; any molecule larger than helium cannot pass through the six-membered ring plane of graphene. Thanks to graphene's high conductivity, chemical stability, and physical barrier properties, graphene-based composite coatings can be applied to the surface of metal bipolar plates in PEMFCs, serving as corrosion protection and electron conduction. The main performance requirements related to bipolar plate materials and coatings include a conductivity greater than 100 S·cm. -1 The corrosion current density was less than 1 μA·cm under both potentiodynamic polarization and 0.6 V constant potential polarization conditions.-2 The interfacial contact resistance remains less than 10 mΩ·cm after 24 hours of constant potential polarization. 2 Therefore, unlike common graphene composite coatings, graphene composite coatings applied to the surface of metal bipolar plates need to contain an extremely high graphene mass ratio to ensure conductivity, which brings challenges such as dispersibility, processability, and interfacial compatibility.

[0006] In addition, the graphene composite coating applied to the surface of metal-based bipolar plates needs to provide long-term corrosion resistance protection for the metal bipolar plates in harsh corrosive environments (80℃, pH≈3). Therefore, a resin with extremely strong bonding force is also needed between the discrete graphene sheets as a binder for the coating to ensure the integrity of the coating. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a graphene-based waterborne radiation-curing coating, a coating method, a metal-based bipolar plate, and a proton exchange membrane fuel cell. Using graphene as the main component and a more environmentally friendly waterborne radiation-curing resin as the organic binder in the coating, the metal-based bipolar plate is provided with corrosion resistance while maintaining conductivity.

[0008] The technical objective of this invention is achieved through the following technical solution:

[0009] A graphene-based waterborne radiation-curing coating includes a graphene derivative and a waterborne radiation-curing resin. The graphene derivative is obtained by oxidative modification of graphene and is stably dispersed in the waterborne radiation-curing resin. The conductivity of the graphene derivative is greater than 200 S / cm.

[0010] Furthermore, the waterborne radiation-curable resin is a waterborne acrylic resin that can be cured by radiation.

[0011] Furthermore, it also includes deionized water used to increase the fluidity of the coating.

[0012] Furthermore, the mass ratio of graphene to waterborne radiation-cured resin is 1:1, 3:2, 2:1, or 4:1.

[0013] This invention also provides a method for coating a graphene-based aqueous radiation-curable coating, used to coat the above-mentioned graphene-based aqueous radiation-curable coating onto the surface of a metal-based bipolar plate to form a graphene-based aqueous radiation-curable coating, the method comprising:

[0014] S1. Clean the surface of the metal-based bipolar plate and then let it air dry;

[0015] S2. A graphene-based waterborne radiation-cured coating is coated onto the surface of a metal-based bipolar plate to form a coating film;

[0016] S3. The coating film is cured in stages, including:

[0017] S31, during the thermosetting stage, water molecules in the coating film evaporate;

[0018] S32, UV curing stage: UV irradiation is used to further cure the coating film;

[0019] In the S33, EB curing stage, EB irradiation is used to completely cure the coating film on the surface of the metal-based bipolar plate to form a graphene-based waterborne radiation-cured coating.

[0020] Furthermore, in step S1, the metal-based bipolar plate is cleaned sequentially with a degreasing agent, dilute sulfuric acid, deionized water, and ethanol.

[0021] Furthermore, in step S2, the coating method for the graphene-based waterborne radiation-curing coating includes any one of the following: rod coating, blade coating, roller coating, and spray coating.

[0022] Furthermore, the graphene derivative content in the graphene-based waterborne radiation-cured coating is 60-80%.

[0023] The present invention also provides a metal-based bipolar plate, wherein a graphene-based aqueous radiation-curing coating is provided on the surface of the metal-based bipolar plate, and the graphene-based aqueous radiation-curing coating is formed on the surface of the metal-based bipolar plate according to the above-described coating method for graphene-based aqueous radiation-curing coating.

[0024] The present invention also provides a proton exchange membrane fuel cell, comprising the above-mentioned metal-based bipolar plate, wherein a graphene-based aqueous radiation-cured coating is provided on the surface of the metal-based bipolar plate.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The graphene-based waterborne radiation-curing coating provided by the present invention forms a conductive coating by mixing graphene derivatives with waterborne radiation-curing resin. The graphene derivatives are stably and uniformly dispersed in the waterborne radiation-curing resin, which can construct a large number of conductive pathways.

[0027] 2. In this invention, the graphene-based waterborne radiation-cured coating formed by the graphene-based waterborne radiation-cured coating has graphene derivatives forming conductive pathways to ensure conductivity; the waterborne radiation-cured resin acts as an adhesive to ensure the integrity of the coating, and together with the graphene, the resin physically blocks the corrosive medium, providing corrosion resistance.

[0028] 3. The graphene-based waterborne radiation-curing coating and graphene-based waterborne radiation-curing coating of the present invention can be used not only for metal-based bipolar plates, but also for electrostatic shielding, electromagnetic shielding and other fields.

[0029] 4. The graphene-based waterborne radiation-curing coating of the present invention can be applied to a metal-based bipolar plate by roller coating, rod coating, spraying, or scraping to form a graphene-based waterborne radiation-curing coating, which is beneficial for roll-to-roll production and has high efficiency. In addition, the graphene-based waterborne radiation-curing coating of the present invention avoids the emission of volatile organic compounds (VOCs) of solvent-based coatings, does not use heavy metal ions, and avoids fire and pollution problems caused by the use of organic solvents, which is in line with the concept of high-efficiency and low-emission production.

[0030] 5. This invention, through a staged curing method, ensures the degree of curing of the coating, avoids the problem of decreased conductivity caused by excessively rapid curing, and the radiation curing (including UV curing and EB curing) has high curing efficiency, occupies little space, and is energy-saving. Attached Figure Description

[0031] Figure 1 These are Fourier transform infrared spectra of the graphene derivative and untreated graphene in Example 4 of this invention.

[0032] Figure 2 This is a surface morphology diagram of the coating in Embodiment 8 of the present invention.

[0033] Figure 3 This is the potentiodynamic polarization diagram of the coatings of Examples 6-8 of the present invention in a sulfuric acid solution at 80°C and pH of approximately 3. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0035] Example 1

[0036] A graphene-based waterborne radiation-curing coating includes a graphene derivative and a waterborne radiation-curing resin. The graphene derivative is obtained by oxidative modification of graphene. The graphene derivative is stably dispersed in the waterborne radiation-curing resin. The conductivity of the graphene derivative is greater than 200 S / cm, and preferably, the conductivity of the graphene derivative is greater than 300 S / cm.

[0037] The mass ratio of graphene to waterborne radiation-cured resin is 1:1, 3:2, 2:1 or 4:1; deionized water can also be added to increase the fluidity of the coating.

[0038] There are two sets of contradictions in graphene-based waterborne radiation-cured coatings. One is the contradiction between the dispersibility and conductivity of graphene. While chemical modification improves the dispersibility, it also destroys its sp2 bonds, resulting in a decrease in conductivity and sacrificing conductivity. The other is that the more resin is added as a binder, the better the bonding force, but the worse the conductivity, because the resin itself is not conductive.

[0039] In this embodiment, although graphene oxidation modification will also destroy the sp2 bonds of graphene, the degree of destruction can be controlled. For metal-based bipolar plates, the conductivity of the metal-based bipolar plates is required to be greater than 100 S / cm. Therefore, the conductivity of graphene derivatives should be at least 200 S / cm. Preferably, the conductivity of graphene derivatives should be at least 300 S / cm to allow room for the addition of non-conductive water-based radiation-cured resin.

[0040] Graphene derivatives are subjected to mild oxidative modification through the following methods:

[0041] a) Dry oxidation: Graphene is treated with ultraviolet ozone for 30-90 minutes.

[0042] b) Wet oxidation: Using any one of sulfuric acid, nitric acid, or hydrogen peroxide as the oxidant, the reaction is carried out for 1-3 hours under the catalysis of copper sulfate or ferric chloride.

[0043] c) Based on the above dry or wet oxidation methods, other molecules can be further grafted, such as silane coupling agents, titanate coupling agents, aluminate coupling agents, p-aminobenzenesulfonic acid, hydroxyethylidene diphosphonic acid, etc.

[0044] Waterborne radiation-curable resins are waterborne acrylic resins that can be cured by radiation, and can also be waterborne polyurethanes, waterborne epoxy acrylates, and waterborne unsaturated polyesters, etc.

[0045] Example 2

[0046] A method for coating a graphene-based waterborne radiation-curable coating is disclosed, which involves coating a graphene-based waterborne radiation-curable coating onto the surface of a metal-based bipolar plate to form a graphene-based waterborne radiation-curable coating. The graphene-based waterborne radiation-curable coating is like the one in Example 1. This example and subsequent examples 3-9 all use a stainless steel bipolar plate as an example for illustration. The method includes:

[0047] S1. Clean the surface of the metal-based bipolar plate to clean the surface of the metal-based bipolar plate and remove the oxide film, then let it dry. When cleaning the metal-based bipolar plate, use degreasing agent, dilute sulfuric acid, deionized water and ethanol in sequence.

[0048] S2. A graphene-based waterborne radiation-curing coating is coated on the surface of a metal-based bipolar plate to form a coating film. The coating method of the graphene-based waterborne radiation-curing coating includes any one of the following: rod coating, blade coating, roller coating, and spray coating.

[0049] S3. The coating film is cured in stages, including:

[0050] S31. During the heat curing stage, water molecules in the coating film evaporate. The heat curing temperature is 100℃-120℃, and the temperature is maintained for 30 minutes.

[0051] S32. In the UV curing stage, UV irradiation is used to further cure the coating film. UV irradiation is performed using a 365nm mercury lamp at 400-2000 mJ / cm². 2 UV irradiation for 5-60 seconds at energy levels;

[0052] In the S33, EB curing stage, EB irradiation is used to completely cure the coating film on the surface of the metal-based bipolar plate to form a graphene-based waterborne radiation-cured coating. EB irradiation is performed at 150kV and 40kGy for less than 1 second for post-curing. The graphene derivative content in the graphene-based waterborne radiation-cured coating is 60-80%.

[0053] In the UV curing stage, the photoinitiator in the coating absorbs ultraviolet light to generate seeds (free radicals or cationic groups) to initiate polymerization, thereby achieving the process of material curing. In the EB curing stage, an electron beam is used as the radiation source. An electron beam is a high-energy charged particle stream. In the EB curing stage, the high-energy charged particle stream directly bombards the molecular chain to generate free radicals to initiate polymerization, thereby converting liquids or low molecular weight compounds into high molecular weight polymers. The curing reaction is fast and the degree of curing is high.

[0054] Traditional thermosetting involves the complete evaporation of water molecules, which reduces the distance between monomer molecules, enhances their interaction, and increases the molecular weight after thermal energy overcomes the energy barrier. However, the degree of thermosetting in irradiated resins is limited, mainly resulting in surface curing.

[0055] In the UV curing process, the photoinitiator in the irradiated resin initiates polymerization by absorbing free radicals or ionic groups generated by UV light, thereby achieving monomer curing. However, graphene has a strong selective absorption of UV light. Therefore, in coatings with a large amount of graphene, the UV light absorbed by the resin is greatly reduced, resulting in a significant decrease in the degree of curing.

[0056] Electron beams (EBs) are a high-energy charged particle stream. During EB curing, an electron beam is directly injected into the curing system, and the high-energy charged particle stream directly bombards the molecular chains to generate free radicals and initiate polymerization, thereby converting low-molecular-weight monomers into high-molecular-weight polymers. Its characteristics include rapid curing speed and high degree of curing. However, the excessively rapid expansion of molecular chains, forming a cross-linked network, increases the steric hindrance of molecules and the distance between conductive particles. Therefore, this invention proposes a three-stage curing process, which ensures the degree of curing while avoiding the problem of decreased conductivity.

[0057] Example 3

[0058] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0059] (1) Graphene was placed in an ultraviolet ozone cleaner for 90 minutes to obtain graphene derivatives.

[0060] (2) Add graphene derivative to deionized water to prepare a 2 mg / mL dispersion. After ultrasonic treatment for 30 minutes, mix graphene and irradiable curable waterborne acrylic resin at a mass ratio of 1:1. After mixing, add water until the solid content of the coating reaches 33% to obtain a graphene-based waterborne radiation-curable coating. The 33% solid content in this embodiment and the following embodiments is just an arbitrary example. The more water added, the greater the fluidity. The fluidity can ensure that the uniformity is increased when preparing the wet film. The water needs to be dried in the end, so the amount of water added will not affect the performance of the coating.

[0061] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0062] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled to be 10 micrometers.

[0063] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes; then, a 365nm mercury lamp is used at 400mJ / cm². 2 The substrate is irradiated with UV light for 5 seconds at 150kV and 40kGy, followed by EB irradiation for less than 1 second of post-curing, ultimately forming a graphene-based waterborne radiation-cured coating on the surface of the metal-based bipolar plate.

[0064] Example 4

[0065] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0066] (1) Graphene was prepared into an aqueous dispersion at a concentration of 2 mg / mL. 1 M (mol / L) dilute sulfuric acid was added to adjust the pH of the aqueous dispersion to 3. Then, copper sulfate pentahydrate was added as a catalyst. 30% hydrogen peroxide solution was diluted to 1% concentration and slowly injected at a rate of 50 ml / h using a micro-injection pump. The reaction was carried out under 300 W, 40 kHz ultrasound and at 40 °C for 70 minutes. The reaction solution was then washed three times with deionized water and ethanol to remove excess surfactant and catalyst. The resulting filter cake was the mildly oxidized graphene derivative.

[0067] (2) Add graphene derivative to deionized water to prepare a concentration of 2 mg / mL. After ultrasonic treatment for 30 minutes, mix graphene and irradiable curable waterborne acrylic resin at a mass ratio of 4:1. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation curable coating.

[0068] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0069] Then, the graphene-based waterborne radiation-cured coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled to be 2 micrometers.

[0070] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes; then, a 365nm mercury lamp is used at 2000mJ / cm². 2 The substrate is irradiated with UV light for 60 seconds at 150kV and 40kGy, followed by EB irradiation for less than 1 second of post-curing, ultimately forming a graphene-based waterborne radiation-cured coating on the surface of the metal-based bipolar plate.

[0071] Example 5

[0072] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0073] (1) Graphene was placed in an ultraviolet ozone cleaner for 90 minutes, then added to deionized water to prepare a 2 mg / mL dispersion, and then 3 times the mass of p-aminobenzenesulfonic acid was added. The reaction was carried out at 80°C for 4 hours. The reaction solution was filtered and washed 3 times with deionized water. The obtained filter cake is the sulfonated modified graphene derivative.

[0074] (2) Add graphene derivative to deionized water to prepare a concentration of 2 mg / mL, sonicate for 30 minutes, and then mix graphene and irradiable waterborne acrylic resin at a mass ratio of 3:2. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation-curable coating.

[0075] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0076] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled at 15 micrometers.

[0077] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes; then, a 365nm mercury lamp is used at 500mJ / cm². 2The substrate is irradiated with UV light for 30 seconds at 150kV and 40kGy, followed by EB irradiation for less than 1 second of post-curing, ultimately forming a graphene-based waterborne radiation-cured coating on the surface of the metal-based bipolar plate.

[0078] Example 6

[0079] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0080] (1) Place the graphene in an ultraviolet ozone cleaner for 90 minutes; then add it to deionized water to prepare a 2 mg / mL dispersion, and then add silane coupling agent KH550 with a mass of 2 times that of the graphene. React at 60°C for 4 hours. After the reaction, the reaction solution is filtered and washed 3 times with deionized water. The obtained filter cake is the graphene derivative modified by the coupling agent.

[0081] (2) Add graphene derivative to deionized water to prepare a 2 mg / mL dispersion, sonicate for 30 minutes, and mix graphene and irradiable waterborne acrylic resin at a mass ratio of 2:1. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation-curable coating.

[0082] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0083] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled at 15 micrometers.

[0084] Then, a curing process is performed, and the drying temperature is controlled at 100℃ for 30 minutes to form a graphene-based water-based coating on the surface of the metal-based bipolar plate.

[0085] Example 7

[0086] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0087] (1) Graphene was prepared into an aqueous dispersion at a concentration of 2 mg / mL. 1 M (mol / L) dilute sulfuric acid was added to adjust the pH value to 3. Copper sulfate pentahydrate was then added as a catalyst. 30% hydrogen peroxide solution was diluted to a concentration of 1% and slowly injected at a rate of 50 ml / h using a micro-injection pump. The reaction was carried out for 70 minutes under ultrasonic waves at a frequency of 40 kHz and a temperature of 40 °C. The reaction solution was then washed three times with deionized water and ethanol to remove excess surfactant and catalyst. The filter cake was then added to deionized water to prepare a dispersion of 2 mg / mL. 25 times the weight of graphene was added as a silane coupling agent, hydroxyethylidene diphosphonic acid. The reaction was carried out at 70 °C for 4 hours. The reaction solution was washed three times with deionized water. The obtained filter cake was the phosphorylated graphene derivative.

[0088] (2) Add graphene derivative to deionized water to prepare a 2 mg / mL dispersion, sonicate for 30 minutes, and mix graphene and irradiable waterborne acrylic resin at a mass ratio of 2:1. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation-curable coating.

[0089] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0090] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled at 15 micrometers.

[0091] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes, and then a 365nm mercury lamp is used at 600mJ / cm². 2 After 60 seconds of UV irradiation at high energy levels, a graphene-based aqueous radiation-cured coating is formed on the surface of a metal-based bipolar plate.

[0092] Example 8

[0093] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0094] (1) Graphene was placed in an ultraviolet ozone cleaner for 90 minutes and then added to deionized water to prepare a 2 mg / mL dispersion. Titanate coupling agent with a mass of 5 times that of graphene was added and refluxed at 100°C for 4 hours. The reaction solution was filtered and washed 3 times with deionized water. The obtained filter cake is the graphene derivative modified with titanate coupling agent.

[0095] (2) Add graphene derivative to deionized water to prepare a 2 mg / mL dispersion, sonicate for 30 minutes, and mix graphene and irradiable waterborne acrylic resin at a mass ratio of 2:1. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation-curable coating.

[0096] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0097] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled at 15 micrometers.

[0098] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes, and then a 365nm mercury lamp is used at 500mJ / cm². 2 After UV irradiation for 30 seconds at energy, EB irradiation is then applied at 150kV and 40kGy for less than 1 second for post-curing, ultimately forming a graphene-based waterborne radiation-cured coating on the surface of the metal-based bipolar plate.

[0099] Example 9

[0100] A method for applying a graphene-based waterborne radiation-cured coating is as follows:

[0101] (1) Place the graphene in an ultraviolet ozone cleaner for 90 minutes, then add it to deionized water to prepare a 2 mg / mL dispersion, add silane coupling agent KH550 with a mass of 2 times that of graphene, react at 60°C for 4 hours, and then filter and wash the reaction solution with deionized water 3 times. The obtained filter cake is the sulfonated modified graphene derivative.

[0102] (2) Add graphene derivative to deionized water to prepare a 2 mg / mL dispersion, sonicate for 30 minutes, and then mix graphene and irradiable waterborne acrylic resin at a mass ratio of 2:1. After mixing, add water until the solid content of the coating reaches 33% to obtain graphene-based waterborne radiation-curable coating.

[0103] (3) The metal-based bipolar plate was cleaned in sequence with degreasing agent, dilute sulfuric acid, deionized water, ethanol, and deionized water;

[0104] Then, the graphene-based waterborne radiation-curing coating was applied to the surface of the metal-based bipolar plate using a rod coating method to form a coating film, with the coating thickness controlled at 15 micrometers.

[0105] Then, a curing process is performed. First, the drying temperature is controlled at 100℃ for 30 minutes. Then, EB irradiation is used to perform post-curing at 150kV and 40kGy for less than 1 second. Finally, a graphene-based waterborne radiation-cured coating is formed on the surface of the metal-based bipolar plate.

[0106] According to the bipolar plate characteristic test method of the People's Republic of China GB / T 20042.6-2011, the corrosion current density and contact resistance of the metal-based bipolar plates in Examples 3 to 9 were tested. The conductivity was tested by the common four-point probe method, and the water resistance was observed after repeated rubbing with a damp cotton cloth. The results are shown in the table below (the table below shows the performance test results of the coating samples of the metal-based bipolar plates in Examples 3-9):

[0107]

[0108]

[0109] The coating conductivity needs to reach 100 S·cm -1 The corrosion current density was below 1 μA·cm under both potentiodynamic polarization and 0.6V constant potential polarization conditions. -2 The interfacial contact resistance remains less than 10 mΩ·cm after 24 hours of constant potential polarization. 2 This meets the industry's performance requirements for fuel cell bipolar plates.

[0110] The test results in the table above show that:

[0111] Only the layer in Example 8 meets all the requirements;

[0112] In Examples 3-5, the graphene content varies. The higher the graphene content, the better the conductivity and the worse the corrosion resistance.

[0113] Examples 6-9 employ different curing methods. Simple thermosetting (Example 6) and thermosetting plus UV curing (Example 7) are insufficient to obtain good corrosion resistance. Thermosetting plus EB curing (Example 9) results in a loss of conductivity due to the rapid curing reaction. Only the coating obtained by using a three-stage curing method of thermosetting plus UV curing and EB curing in Example 8 has the required overall performance.

[0114] Appendix Figure 1 The graphene derivative in Example 4 and the untreated graphene are Fourier transform infrared spectra. It can be seen from the figure that the intensity of the modified graphene has changed significantly, the intensity has decreased, and the dispersibility has increased.

[0115] Figure 2This is a surface morphology diagram of the coating in Example 8. The graphene derivative is spread on the surface of the metal-based bipolar plate, which plays a role in protecting the metal substrate and conducting electrons.

[0116] Figure 3 This is the potentiodynamic polarization diagram of the coatings in Examples 6-8 in a sulfuric acid solution at 80°C and pH approximately 3. Figure 3 As can be seen from the results, under the same environmental conditions, the corrosion resistance of the coating in Example 8, which uses thermosetting + UV curing + EB curing, is better than that of the coating in Example 7, which uses thermosetting + UV curing.

[0117] The corrosion resistance of the coating obtained by thermosetting and UV curing in Example 7 is better than that of the coating obtained by thermosetting in Example 6.

[0118] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A graphene-based waterborne radiation-cured coating, characterized in that, The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The aqueous radiation-curable resin is a radiation-curable aqueous acrylic resin; and the mass ratio of the graphene derivative to the aqueous radiation-curable resin is 1:1, 3:2, 2:1 or 4:

1. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm.

2. A graphene based waterborne radiation curable coating according to claim 1, characterized in that, The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm.

3. A coating method of a graphene-based waterborne radiation-cured coating layer for coating a graphene-based waterborne radiation-cured coating material on a surface of a metal-based bipolar plate to form a graphene-based waterborne radiation-cured coating layer, characterized by, The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm. The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm.

4. A method of coating a graphene-based waterborne radiation-cured coating according to claim 3, characterised in that, The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm.

5. A method of coating a graphene-based waterborne radiation-cured coating according to claim 3, characterized in that, The graphene derivative is obtained by mild oxidation modification of graphene, and the graphene derivative is stably dispersed in the aqueous radiation-curable resin, and the conductivity of the graphene derivative is greater than 200 S / cm.

6. A method of coating a graphene-based waterborne radiation-cured coating according to claim 3, characterized in that, ​ 7. A metal-based bipolar plate, characterized by ​ 8. A proton exchange membrane fuel cell characterized by ​

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