Application of Graphene in Waterborne Coatings

Water-based paint is an environmentally friendly paint advocated by the state, but some properties are not as good as the corresponding solvent-based paint, which affects its development

Water-dispersed modified graphene modified with titanate coupling agent

According to the general method, graphite is made into graphene oxide, and titanate and hydrazine hydrate are respectively added to the graphene oxide dispersion liquid, and the reaction occurs under the heating method in a water bath, so that the graphene oxide is reduced and the titanate coupling agent is grafted at the same time.

Because the titanate coupling agent has carried out surface modification on graphene oxide, no agglomeration occurs, so the graphene aqueous dispersion has high stability, can be stored for a long time, and is suitable for the preparation of composite materials and coating materials

Graphene and matrix resin blend composite water-based coating

1.

Graphene/polyester resin composite water-based conductive coating

2.

The graphene-modified wear-resistant water-based glass coating consists of two components, the first component is a matrix film-forming material, and the second component is a curing agent

3.

The graphene oxide prepared by the Hummers method is added to the acrylate polymer emulsion, the selected auxiliary agent is added, the cement is added in proportion, and the mixture is stirred and dispersed to prepare a graphene oxide-modified polymer cement waterproof coating

4.

4.
1 Graphene/aqueous polyurethane nanocomposite emulsion

Polyether polyol (N210) dehydrated in vacuum was reacted with TDI to prepare polyurethane prepolymer, dimethylolpropionic acid was added to introduce hydrophilic carboxyl groups, triethylamine was added to neutralize the base, and graphene oxide aqueous solution was added to remove Ionized water and ethylenediamine are subjected to an emulsification reaction, and after acetone is distilled off under reduced pressure, a vitamin C solution is added dropwise to perform an in-situ reduction reaction to obtain graphene/aqueous polyurethane nanocomposite latex resin
.
The latex resin can be applied to the fields of electrostatic protection, anti-corrosion coating, architectural coatings, etc.
The process of the invention is simple, environmentally friendly, and suitable for large-scale production
.

4.
2 Graphene/TiO2 composite modified waterborne polyurethane antibacterial coating

As a kind of photocatalytic nanomaterials, nano-TiO2 has antibacterial and sterilization effect, but its absorption rate for visible light is low, and nanoparticles tend to aggregate, which greatly reduces its sterilization effect
.
In the antibacterial coating containing nano-TiO2, the introduction of graphene below 5% can significantly improve the visible light absorption rate of the coating, and enhance the photocatalytic activity and antibacterial and sterilization capabilities of nano-TiO2, so that the modified water-based polyurethane can be used for antibacterial and sterilization.
The overall performance has been greatly improved
.
And has good surface properties, water resistance and mechanical properties
.

4.
3 Graphene/polyurethane in-situ polymerized water-based conductive coatings

Compared with traditional carbon-based conductive fillers (carbon black, graphite, carbon nanotubes, carbon fibers, etc.
), graphene has better electrical conductivity and mechanical properties
.

Graphene oxide was modified by amination with diamine, and then the conjugated conductive system of graphene was restored by chemical reduction.
The graphene-containing water-based polyurethane was polymerized in situ by -NH and -NCO-terminated on the surface of graphene to obtain graphene-containing waterborne polyurethane conductive coatings
.

The conductive coating has the properties of anti-radiation, anti-static, anti-corrosion, wear-resisting, etc.
, and can be used for the surface of polymer materials, metal materials, textile materials and the like
.

4.
4 Preparation of modified graphene/waterborne polyurethane nanocomposite coatings by sol-gel technology

Xin Wang from University of Science and Technology of China published their research paper in "Surface & Coatings Technology" in 2012: Preparation of Modified Graphene/Waterborne Polyurethane Composite Nanocoatings by Sol-Gel Technology, divided into 3 parts:

(1) Preparation of silane-modified graphene nanofilms
.
Graphene oxide (GO) was prepared by Hummers method, followed by chemical reduction of GO aqueous dispersion with hydrazine hydrate to GNS, followed by DCC (N,N'-dicyclohexylcarbodiimide) and 3-aminopropyltriethyl The functional modification of oxysilane (APTES) was carried out by ultrasonic dispersion for 1 h, and the reaction was stirred at 70 °C for 24 h.
After post-treatment, the graphene nanofilm f-GNS modified with APTES function was obtained
.

(2) Preparation of silane APTES-terminated waterborne polyurethane (WPU)
.
Use isophorone diisocyanate (IPDI), polyoxypropylene glycol, diethylene glycol and trimethylolpropane mixed polyol to synthesize PU prepolymer, then react with dimethylolpropionic acid, and then add APTES to react, The APTES-terminated waterborne polyurethane (WPU) was obtained with a yield of 86.
3% and a number average molecular weight of 28 600 (determined by GPC)
.

(3) f-GNS/WPU nanocomposite coatings were prepared by sol-gel technology
.
The f-GNS powder was dispersed in deionized water with the help of ultrasonic wave to make a suspension, the APTES-terminated WPU was added to it and mixed together, and the pH value was adjusted with triethylamine to prepare the f-GNS/WPU nanocomposite coating
.

The structures of GO and f-GNS were characterized by 1H-NMR, FTIR, XPS, GPC, AFM, HRTEM, etc.
, which basically verified the molecular structure and reaction process shown in Figure 1, and the product structure of f-GNS/WPU nanocomposite coatings and composition
.
T1, T2, and T3 in the nanocomposites represent mono-, di-, and trisubstituted silane linkages, confirming the polycondensation reaction between APTES-terminated WPU and f-GNS adjacent siloxane molecules, forming covalent bonds
.

Fig.
1 Preparation of f-GNS/WPU nanocomposite coatings by sol-gel method

Epilogue

1.
Graphene has unique properties, and the research and development boom is booming around the world

Graphene is the "thinest" crystalline material found in the world today, with a thickness of only 1 carbon atom.
It is also one of the "hardest" materials, and has high electrical conductivity and high thermal conductivity
.
Prediction has immeasurable application prospects in aerospace, space exploration, marine development, national defense industry, and national economy
.

2.
Graphene shows new promise in modifying coating properties

It has very attractive potential prospects for graphene in functional coatings such as electrical conductivity, anticorrosion, flame retardant, thermal conductivity and high strength
.

Graphene and various coating resins are compounded by physical blending, in-situ polymerization and sol-gel technology; or modified with coupling agents, or in-situ polymerization and other processes
.
These processes have been proved feasible in modified waterborne coatings, and the performance improvement is obvious
.
The performance of water-based coatings modified by graphene is expected to "go to the next level", and its further development can be expected
.

3.
The pace of research and development of graphene-modified coatings is beginning to take place.
To correctly promote the development of graphene production and application, the development boom continues to heat up, but it should be treated calmly
.

For production enterprises, there is a lot of technical work to be done to determine whether the graphene production technology reaches the most advanced in the world, whether it meets the requirements of clean and civilized production process, and whether the cost is reasonable
.
The application of graphene in coatings has a lot of research work and patents published in China
.
There is a lot of room for research and development in the composite method of graphene and coating resin, the selection of additives, and the improvement of functionality
.
Most of the work and patents published in China for graphene-modified water-based coatings are laboratory results.
To achieve practicality and industrialization, more investment is required, and there is a lot of research and development work to be done
.