WO2021097660A1

WO2021097660A1 - Method for preparing graphene composite coating

Info

Publication number: WO2021097660A1
Application number: PCT/CN2019/119427
Authority: WO
Inventors: 沈磊
Original assignee: 南京先进生物材料与过程装备研究院有限公司
Priority date: 2019-11-19
Filing date: 2019-11-19
Publication date: 2021-05-27

Abstract

A method for preparing a graphene composite coating, comprising: step 1, preparation of graphene oxide; step 2, preparation of a graphene oxide polypyrrole compound; step 3, preparation of a reduced graphene oxide polypyrrole compound; and step 4, preparation of a graphene composite coating. The graphene composite coating prepared by the method has good water penetration resistance, high protection capability, and an excellent anti-corrosion effect, and can be used as a heavy-duty anti-corrosion coating in relatively harsh corrosive environments such as ships and bridges.

Description

Method for preparing graphene composite coating

Technical field

The invention relates to the technical field of preparation of composite coatings, in particular to a preparation method of graphene composite coatings.

Background technique

Graphene is a two-dimensional carbon nanomaterial with a hexagonal honeycomb lattice composed of carbon atoms and sp ^{2 hybrid orbitals.} In fact, graphene exists in nature, but it is difficult to peel off a single-layer structure. Layers of graphene are stacked to form graphite, and 1 mm thick graphite contains about 3 million layers of graphene. A lightly stroked pencil on the paper may leave traces of several layers or even just one layer of graphene. In 2004, two scientists, Andre Gaim and Konstantin Novoslov, at the University of Manchester in the United Kingdom, discovered that they could use a very simple method to obtain thinner and thinner graphite flakes. They peeled off the graphite flakes from the highly oriented pyrolytic graphite, then glued the two sides of the flakes to a special kind of tape, and peeled off the tape to split the graphite flakes in two. Keep doing this, so the flakes get thinner and thinner, and finally, they get a flake composed of only one layer of carbon atoms, which is graphene. Since then, new methods of preparing graphene have emerged endlessly. In 2009, Andrei Geim and Konstantin Novoselov discovered the integer quantum Hall effect and the quantum Hall effect at room temperature in single-layer and double-layer graphene systems, respectively. Won the 2010 Nobel Prize in Physics. Before the discovery of graphene, most physicists believed that thermodynamic fluctuations did not allow any two-dimensional crystals to exist at a finite temperature. Therefore, its discovery immediately shocked the academic community of condensed matter physics. Although both theoretical and experimental circles believe that a perfect two-dimensional structure cannot exist stably at non-absolute zero degrees, single-layer graphene can be prepared in experiments. On March 31, 2018, China’s first fully automated mass-produced graphene organic solar optoelectronic device production line was launched in Heze, Shandong. The project mainly produces graphene organic solar cells that can generate electricity under low light, breaking the application limitations and angles. Sensitive and difficult to shape the three major solar power problems. The chemical properties of graphene are similar to graphite, and graphene can adsorb and desorb various atoms and molecules. When these atoms or molecules are used as donors or acceptors, the concentration of graphene carriers can be changed, while graphene itself can maintain good conductivity. But when other substances are adsorbed, such as H ⁺ and OH ^- , some derivatives will be produced, which will make the conductivity of graphene worse, but no new compounds will be produced.

The organic polymer or resin in the composite coating can improve the disadvantages of inorganic materials (such as silica sol) that become hard and brittle after film formation, and at the same time avoid or alleviate the problems of easy aging of organic materials, poor resistance to pollution, and poor heat resistance. The performance stability and anti-corrosion effect of the existing ordinary composite coatings are difficult to significantly improve. Therefore, it is necessary to provide a method for preparing graphene composite coatings.

Summary of the invention

In order to overcome the defects in the prior art, a method for preparing graphene composite coatings is provided.

The present invention is realized through the following schemes:

A preparation method of graphene composite coating, calculated in parts by mass, the method includes the following steps:

Step 1. Preparation of graphene oxide: add 5-7 parts of sodium nitrate, 1-3 parts of flake graphite, and 3-5 parts of potassium permanganate to 100 parts of concentrated sulfuric acid, mix well and ice bath for 1-3 hours , Then heat to 100-110°C for reaction for 1-3 hours, then dissolve the whole reaction system in 150-250 parts of water, add hydrogen peroxide until the solution is golden yellow, wash with hydrochloric acid and demineralized water for several times, centrifuge, adjust the pH After the value reaches 5-6, it is dried to obtain graphene oxide;

Step 2. Preparation of graphene oxide polypyrrole composite: weigh 0.4-0.6 parts of graphene oxide composite prepared in step 1, 0.4-0.6 parts of N-vinylamide polymer, and add 60-80 parts of hydrochloric acid Under ultrasonic assisted dispersion for 1 hour, then put the reaction system in an ice bath while adding pyrrole monomer liquid dropwise and stirring for 1 hour. Add 100 parts of ammonium persulfate hydrochloric acid solution dropwise to the resulting mixture emulsion and react for 18-30 hours in ice water. , Using acetone and deionized water for centrifugal washing to obtain graphene oxide polypyrrole compound;

Step 3. Preparation of reduced graphene oxide-polypyrrole compound: weigh 0.5-0.7 parts of graphene oxide-polypyrrole compound, add it to 200 parts of deionized water for ultrasonic assisted dispersion for 1 hour, and then add 0.3-0.5 parts of reduction The product is stirred for 1 hour; the product is placed in an oil bath to keep the temperature at 120-130°C and condensed and refluxed for 2-4 hours. After filtration, add acetone and deionized water for centrifugal washing. After drying, the reduced graphene oxide polypyrrole is obtained. Complex;

Step 4: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix uniformly, and use ultrasonic to assist dispersion, then add 7 parts of water-based film-forming aids and 0.15 parts of reduced graphene oxide polypyrrole compound prepared in step 3 , Stir under the assistance of ultrasonic for 4 hours to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir under the assistance of ultrasonic for 2 hours to obtain the second component; After mixing the first component and the second component, stir for 2 hours under the assistance of ultrasonic wave, and add 0.2 part of emulsifier, 0.2 part of dispersant, 0.5 part of defoaming agent, 0.2 part of wetting agent in sequence, and stir and mix to obtain graphene. Composite coating.

In step 1, the water is ultrapure water or demineralized water.

In step 2, the N-vinylamide polymer is polyvinylpyrrolidone.

In step 2, the molar concentration of the hydrochloric acid is 0.1 mol/L.

In step three, the reducing agent is hydrazine hydrate.

The water-based film-forming aid includes 2 parts of ethylene glycol butyl ether, 0.5 parts of barium sulfate, 2.5 parts of talc, and 2 parts of calcium carbonate.

The emulsifier is alkylphenol polyoxyethylene ether.

The beneficial effects of the present invention are:

The graphene composite coating prepared by the preparation method of the graphene composite coating of the present invention has good water penetration resistance, strong protection ability, and excellent anti-corrosion effect, and can be used as a heavy-duty anti-corrosion coating for relatively harsh applications such as ships and bridges. In a corrosive environment. In addition, the graphene composite coating of the present application does not contain heavy metal elements such as In and Sn, does not cause the problem of heavy metal pollution, and has simple preparation process requirements and low cost, which is conducive to large-scale industrial production.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments:

Step 4: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix uniformly, and use ultrasonic to assist dispersion, then add 7 parts of water-based film-forming aids and 0.15 parts of reduced graphene oxide polypyrrole compound prepared in step 3 , Stir under the assistance of ultrasonic for 4 hours to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir under the assistance of ultrasonic for 2 hours to obtain the second component; After mixing the first component and the second component, stir for 2 hours under the assistance of ultrasonic wave, and add 0.2 part of emulsifier, 0.2 part of dispersant, 0.5 part of defoaming agent, 0.2 part of wetting agent in sequence, and stir and mix to obtain graphene. Composite coating. The selection of dispersant, defoamer, and wetting agent can be considered based on production costs, customer requirements, etc., which are well-known technologies to those skilled in the art and will not be repeated here.

In step 1, the water is ultrapure water or demineralized water.

In step 2, the N-vinylamide polymer is polyvinylpyrrolidone.

In step 2, the molar concentration of the hydrochloric acid is 0.1 mol/L.

In step three, the reducing agent is hydrazine hydrate.

The emulsifier is alkylphenol polyoxyethylene ether.

The technical solution of the present application uses the reduction of hydrazine hydrazine to prepare a reduced graphene-polypyrrole composite product, where the polypyrrole uses graphene as a template to polymerize on the surface of the graphene and between the layers, making the graphene sheets more disordered Arrangement and increased dispersion; fully filled in epoxy resin, repair the void defects of the coating coating, enhance the compactness of the coating coating, have good water permeability, strong protection ability, and excellent anti-corrosion effect. As a heavy-duty anticorrosive coating, it is used in relatively harsh corrosive environments such as ships and bridges.

The application will be further elaborated below in conjunction with specific examples and comparative examples.

Example 1

Step 1. Preparation of graphene oxide: add 7 parts of sodium nitrate, 2 parts of flake graphite, and 3 parts of potassium permanganate to 100 parts of concentrated sulfuric acid, mix well and ice bath for 2 hours, then heat to 100-110°C React for 2 hours, then dissolve the whole reaction system in 250 parts of demineralized water, add hydrogen peroxide until the solution is golden yellow, wash with hydrochloric acid and demineralized water, centrifuge for several times, adjust the pH to 5-6 and then dry to obtain oxidation Graphene;

Step 2. Preparation of graphene oxide polypyrrole compound: weigh 0.5 part of graphene oxide compound prepared in step 1 and 0.4 part of polyvinylpyrrolidone, add to 80 parts of hydrochloric acid for ultrasonic assisted dispersion for 1 hour, and then disperse the reaction system In an ice bath, the pyrrole monomer liquid was added dropwise and stirred for 1 hour, 100 parts of ammonium persulfate hydrochloric acid solution was added dropwise to the obtained mixture emulsion and reacted in ice water for 24 hours, and then centrifuged and washed with acetone and deionized water to obtain Graphene oxide polypyrrole compound;

Step 3. Preparation of reduced graphene oxide-polypyrrole compound: Weigh 0.6 parts of graphene oxide-polypyrrole compound, add it to 200 parts of deionized water for ultrasonic assisted dispersion for 1 hour, then add 0.3 part of hydrazine hydrate and stir for 1 Hours; Put the product in an oil bath to keep the temperature at 120-130°C and condense and reflux for 3 hours. After filtration, add acetone and deionized water to centrifuge to wash, and dry to obtain reduced graphene oxide polypyrrole compound;

Step 4: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix uniformly, and use ultrasonic to assist dispersion, then add 7 parts of water-based film-forming aids and 0.15 parts of reduced graphene oxide polypyrrole compound prepared in step 3 , Stir under the assistance of ultrasonic for 4 hours to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir under the assistance of ultrasonic for 2 hours to obtain the second component; After the first component and the second component are mixed, stir for 2 hours under the assistance of ultrasound, and add 0.2 parts of alkylphenol polyoxyethylene ether, 0.2 parts of dispersant, 0.5 parts of antifoaming agent, and 0.2 parts of wetting agent in sequence, and stir and mix The graphene composite coating can be obtained evenly.

Example 2

Step 1. Preparation of graphene oxide: add 5 parts of sodium nitrate, 3 parts of flake graphite, and 4 parts of potassium permanganate to 100 parts of concentrated sulfuric acid, mix well and ice bath for 1-3 hours, and then heat to 100- React at 110°C for 3 hours, then dissolve the whole reaction system in 150 parts of demineralized water, add hydrogen peroxide until the solution is golden yellow, wash with hydrochloric acid and demineralized water for several times, centrifuge, adjust the pH to 5-6 and then dry. Obtain graphene oxide;

Step 2. Preparation of graphene oxide polypyrrole compound: Weigh 0.6 part of graphene oxide compound prepared in step 1 and 0.5 part of polyvinylpyrrolidone, add them to 60 parts of hydrochloric acid for ultrasonic assisted dispersion for 1 hour, and then disperse the reaction system In an ice bath, the pyrrole monomer liquid was added dropwise and stirred for 1 hour. 100 parts of ammonium persulfate hydrochloric acid solution was added dropwise to the obtained mixture emulsion and reacted in ice water for 18 hours. The mixture was washed with acetone and deionized water by centrifugation. Graphene oxide polypyrrole compound;

Step 3. Preparation of reduced graphene oxide polypyrrole compound: Weigh 0.7 parts of graphene oxide polypyrrole compound, add it to 200 parts of deionized water for ultrasonic assisted dispersion for 1 hour, then add 0.4 part of hydrazine hydrate and stir for 1 Hours; Put the product in an oil bath to keep the temperature at 120-130°C and condense and reflux for 2 hours. After filtration, add acetone and deionized water to centrifuge to wash, and dry to obtain reduced graphene oxide polypyrrole compound;

Step 4: Preparation of graphene composite coating:

Example 3

Step 1. Preparation of graphene oxide: add 6 parts of sodium nitrate, 1 part of flake graphite, and 5 parts of potassium permanganate to 100 parts of concentrated sulfuric acid, mix well and ice bath for 1 hour, then heat to 100-110°C React for 1 hour, then dissolve the whole reaction system in 200 parts of demineralized water, add hydrogen peroxide until the solution is golden yellow, wash with hydrochloric acid and demineralized water, centrifuge for several times, adjust the pH to 5-6 and then dry to obtain oxidation Graphene;

Step 2. Preparation of graphene oxide polypyrrole compound: weigh 0.4 part of graphene oxide compound prepared in step 1 and 0.6 part of polyvinylpyrrolidone, add to 70 parts of hydrochloric acid for ultrasonic assisted dispersion for 1 hour, and then disperse the reaction system In an ice bath, the pyrrole monomer liquid was added dropwise and stirred for 1 hour, 100 parts of ammonium persulfate hydrochloric acid solution was added dropwise to the obtained mixture emulsion and reacted in ice water for 30 hours, and then centrifuged and washed with acetone and deionized water to obtain Graphene oxide polypyrrole compound;

Step 3. Preparation of reduced graphene oxide polypyrrole compound: Weigh 0.5 part of graphene oxide polypyrrole compound, add it to 200 parts of deionized water for ultrasonic assisted dispersion for 1 hour, then add 0.5 part of hydrazine hydrate and stir for 1 Hours; Put the product in an oil bath to keep the temperature at 120-130°C and condense and reflux for 3 hours. After filtration, add acetone and deionized water to centrifuge to wash, and dry to obtain reduced graphene oxide polypyrrole compound;

Step 4: Preparation of graphene composite coating:

Comparative example 1

Step 3: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix them evenly, and use ultrasonic to assist dispersion, and then add 7 parts of water-based film-forming aids and 0.15 parts of graphene oxide polypyrrole compound prepared in step two to it. Stir for 4 hours under the assistance of ultrasound to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir under the assistance of ultrasound for 2 hours to obtain the second component; After mixing the components and the second component, stir for 2 hours under the assistance of ultrasound, and add 0.2 parts of alkylphenol polyoxyethylene ether, 0.2 parts of dispersant, 0.5 parts of defoamer, and 0.2 parts of wetting agent in sequence, and stir and mix evenly The graphene composite coating is obtained.

Comparative example 2

Step 2: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix them evenly with ultrasonic assisted dispersion. Then add 7 parts of water-based film-forming aids and 0.15 parts of graphene oxide prepared in step one to it, under the assistance of ultrasonic Stir for 4 hours to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir for 2 hours with the assistance of ultrasonic waves to obtain the second component; After the two components are mixed, stir for 2 hours under the assistance of ultrasonic wave, and add 0.2 part of alkylphenol polyoxyethylene ether, 0.2 part of dispersant, 0.5 part of defoaming agent, 0.2 part of wetting agent in sequence, stir and mix evenly to obtain graphene Composite coating.

Comparative example 3

A preparation method of epoxy resin coating, calculated in parts by mass, the method includes the following steps:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix them evenly, and use ultrasonic to assist dispersion, then add 7 parts of water-based film-forming aids to it, and stir under the assistance of ultrasonic for 4 hours to obtain the first component; Mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir for 2 hours under the assistance of ultrasound to obtain the second component; mix the obtained first and second components and then stir under the assistance of ultrasound For 2 hours, add 0.2 parts of alkylphenol polyoxyethylene ether, 0.2 parts of dispersant, 0.5 parts of defoamer, and 0.2 parts of wetting agent in sequence, stir and mix uniformly to obtain oxygen resin coating.

Common A3 carbon steel was used as the corrosion target to test the anti-corrosion performance parameters of the coatings prepared in different examples and comparative examples of this application, in which the coatings of Examples 1-3 and Comparative Examples 1-3 were uniformly coated with the same thickness On the surface of A3 carbon steel, the moisture permeability and oxygen permeability of different coatings were measured with a gas permeability tester; the CS300 electrochemical test system developed by Huazhong University of Science and Technology was used to compare Examples 1-3 and Comparative Example 1- The coating of 3 is uniformly coated on the surface of A3 carbon steel with the same thickness, and the polarization curve is tested under the condition of 3.5% NaCl solution. The results are shown in Table 1. Among them, the specific test process, test method, and test principle are well-known technologies, and will not be repeated here.

Table 1 Anti-corrosion performance parameters of coatings prepared in different examples and comparative examples

It can be seen from the water permeability and oxygen permeability that Comparative Example 3 prepared a pure epoxy resin coating. The coating prepared by this coating is prone to microporosity during the solvent evaporation process, resulting in both water permeability and oxygen permeability. Compared with the graphene composite coating of Examples 1-3, the water permeability and oxygen permeability of Comparative Example 3 are more than twice that of the graphene composite coating. In Comparative Example 2, graphene oxide is added as a filler. Graphene oxide with a high specific surface area increases the internal interface area of the epoxy resin, so that a small amount of gas molecules stay in the coating, and the oxygen and moisture permeability rate decreases. In Comparative Example 1, a graphene oxide polypyrrole compound was added as a filler, and the graphene oxide polypyrrole compound further increased the internal interface area of the epoxy resin, so that the oxygen and moisture permeation rate continued to decrease. Examples 1-3 added reduced graphene oxide polypyrrole compound as the filler of the epoxy resin. After the compound reduced graphene oxide, the agglomeration phenomenon of the reduced graphene oxide was improved by reducing the graphene oxide in the epoxy resin. The interface area is further increased, which greatly reduces the permeation rate of oxygen and moisture, and improves the gas barrier performance of the coating of the graphene composite coating prepared in the present application.

It can be seen from the corrosion potential and the corrosion current density that in Comparative Example 3, the corrosion potential of the coating prepared by pure epoxy resin coating is -0.762V, and the corrosion current density is 85.62μA·cm ^-2 . In Comparative Example 2, adding graphene oxide to the epoxy resin as a filler, the corrosion current density is still high, and the corrosion resistance is poor. Comparative example 1, adding graphene oxide-polypyrrole composite to epoxy resin as filler, graphene oxide-polypyrrole composite nanoparticles increase the shielding performance of the coating and reduce the porosity, and its corrosion potential and corrosion current density have been compared Close to the value of Example 1-3. Examples 1-3 added reduced graphene oxide polypyrrole compound as the filler of epoxy resin. The dispersion of reduced graphene oxide polypyrrole compound epoxy resin was better than that of graphene polypyrrole compound, which could be used in carbon A protective layer is formed on the steel surface to prevent hydrogen evolution reactions and improve the corrosion resistance of the graphene composite coating. At this time, the graphene composite coating has the lowest corrosion current density and the best anti-corrosion performance.

Although the technical solutions of the present invention have been described and enumerated in more detail, it should be understood that for those skilled in the art, it is important for those skilled in the art to modify the above-mentioned embodiments or adopt equivalent alternatives. Obviously, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of the present invention.

Claims

A preparation method of graphene composite coating, characterized in that, calculated in parts by mass, the method includes the following steps:

Step 1. Preparation of graphene oxide: add 5-7 parts of sodium nitrate, 1-3 parts of flake graphite, and 3-5 parts of potassium permanganate to 100 parts of concentrated sulfuric acid, mix well and ice bath for 1-3 hours , Then heat to 100-110°C for 1-3 hours, then dissolve the whole reaction system in 150-250 parts of water, add hydrogen peroxide until the solution is golden yellow, wash with hydrochloric acid and demineralized water, centrifuge for several times, adjust the pH After the value reaches 5-6, it is dried to obtain graphene oxide;

Step 2. Preparation of graphene oxide polypyrrole composite: weigh 0.4-0.6 parts of graphene oxide composite prepared in step 1, 0.4-0.6 parts of N-vinylamide polymer, and add 60-80 parts of hydrochloric acid Under ultrasonic assisted dispersion for 1 hour, then put the reaction system in an ice bath while adding pyrrole monomer liquid dropwise and stirring for 1 hour. Add 100 parts of ammonium persulfate hydrochloric acid solution dropwise to the resulting mixture emulsion and react for 18-30 hours in ice water. , Using acetone and deionized water for centrifugal washing to obtain graphene oxide polypyrrole compound;

Step 3. Preparation of reduced graphene oxide-polypyrrole compound: weigh 0.5-0.7 parts of graphene oxide-polypyrrole compound, add it to 200 parts of deionized water for ultrasonic assisted dispersion for 1 hour, and then add 0.3-0.5 parts of reduction The product is stirred for 1 hour; the product is placed in an oil bath to keep the temperature at 120-130°C and condensed and refluxed for 2-4 hours. After filtration, add acetone and deionized water for centrifugal washing. After drying, the reduced graphene oxide polypyrrole is obtained. Complex;

Step 4: Preparation of graphene composite coating:

Weigh 20 parts of water-based epoxy resin emulsion and 20 parts of deionized water and mix uniformly, and use ultrasonic to assist dispersion, then add 7 parts of water-based film-forming aids and 0.15 parts of reduced graphene oxide polypyrrole compound prepared in step 3 , Stir under the assistance of ultrasonic for 4 hours to obtain the first component; mix 18 parts of water-based epoxy curing agent and 12 parts of deionized water uniformly, and stir under the assistance of ultrasonic for 2 hours to obtain the second component; After mixing the first component and the second component, stir for 2 hours under the assistance of ultrasonic wave, and add 0.2 part of emulsifier, 0.2 part of dispersant, 0.5 part of defoaming agent, 0.2 part of wetting agent in sequence, and stir and mix to obtain graphene. Composite coating.
The method for preparing a graphene composite coating according to claim 1, wherein in step 1, the water is ultrapure water or demineralized water.
The method for preparing a graphene composite coating according to claim 1, wherein in step 2, the N-vinylamide polymer is polyvinylpyrrolidone.
The method for preparing a graphene composite coating according to claim 1, wherein in step 2, the molar concentration of the hydrochloric acid is 0.1 mol/L.
The method for preparing a graphene composite coating according to claim 1, wherein in step three, the reducing agent is hydrazine hydrate.
The method for preparing a graphene composite coating according to claim 1, wherein the water-based film-forming aid comprises 2 parts of ethylene glycol butyl ether, 0.5 parts of barium sulfate, 2.5 parts of talc powder, and 2 parts of carbonic acid. calcium.
The method for preparing a graphene composite coating according to claim 1, wherein the emulsifier is alkylphenol polyoxyethylene ether.