Research progress of waterborne antistatic coatings

LI Zhanqi1, ZHOU Meng2, CHEN Shuai*2, FU Changqing3, SHEN Liang1,2

（1.
Department of Coatings and Polymers, College of Chemistry and Chemical Engineering, Jiangxi Normal University of Science and Technology, Nanchang 330013, China; 2.
Jiangxi Waterborne Coating Engineering Laboratory, Nanchang 330013, China; 3.
Jiangxi Provincial Key Laboratory of Organic Functional Molecules, Nanchang 330013)

Abstract: ESD protection is one of the key process technologies commonly used in industrial production, aerospace, plastic packaging, electronic products, textiles and other fields, and its core is to develop a high-performance antistatic coating
.
Waterborne antistatic coatings have the advantages of green environmental protection and are an important direction and trend
in the development of this field.
This paper reviews the research progress in this field in recent years mainly from the perspective of the source of electrical properties of waterborne antistatic coatings (antistatic dosage form and conductive filler type), and further discusses the positive progress in the research of antistatic and hydrophobic, anti-corrosion and sterilization and bio-based material substitution, and finally looks forward to the future development direction of waterborne antistatic coatings online coatingol.
com
.

Keywords: electrostatic protection; Antistatic coating; water-based coatings; conductive fillers; Green environmental protection

Standardized bibliographic format of references:

LI Zhanqi, ZHOU Meng, CHEN Shuai, et al.
Research Progress of Waterborne Antistatic Coatings[J].
Coatings Industry, 2022, 52(11): 61-67.

LI Z Q,ZHOU M,CHEN S,et al.
Research progress of waterborne antistatic coatings[J].
Paint & Coatings Industry,2022, 52(11):61-67.
 

Click the DOI number to download and read the full text: 10.
12020/j.
issn.
0253-4312.
2022.
11.
61

Static electricity can be generated by contact, induction, friction, etc.
and accumulate on the surface of insulating materials such as plastics, glass, paper, fabrics, etc.
, resulting in dust adsorption, breakdown of electronic components, and even safety hazards
such as combustion or explosion.
The human body is exposed to an electrostatic environment for a long time, and it is prone to adverse reactions
such as insomnia and depression.
Therefore, electrostatic protection has become one of the
key technologies that must be considered in many fields such as industrial production, aerospace, plastic packaging, electronics, textiles and so on.
Its core is to develop antistatic coating materials
with surface resistivity of about 105~1012 Ω or volume resistivity of about 104~1011 Ω·cm.
Antistatic coatings generally include polymers as film-forming substances, and antistatic agents or conductive fillers as functional additives, and control the electrical, film-forming, mechanical, thermal and other comprehensive properties
of the coating through the regulation of formula components.

Antistatic agent (ASA) belongs to surfactant materials, both small molecules and polymer compounds, the antistatic coating performance prepared by it is humidity-dependent and generally affected by environmental conditions such as temperature
.
In contrast, conductive fillers come from a wide range of sources, including inorganic carbon-based materials, metals and their oxides, as well as conducting polymers (CPs) and their composite systems
.
The coating surface prepared by it not only has intrinsic antistatic function (using its own conductive network to dissipate electrostatic charge), but also has conductivity, electromagnetic shielding, anti-corrosion and other functions
.
At the same time, compared with the organic solvent-based system, the water-based system has the comprehensive advantages of non-toxic, green environmental protection, safe storage, transportation and construction, low cost, etc.
, which is the focus and development trend of the current antistatic coating research, and the market demand is growing
.

In view of the continuous development of waterborne technology of antistatic coatings, this paper reviews the research progress of general-purpose waterborne antistatic coatings, multifunctional systems with antistatic and hydrophobic, bactericidal, anticorrosion, etc.
, and biomass alternative fossil raw material systems (Figure 1), in order to promote the development of this field and provide some ideas and guidance
for future research.

1 Universal waterborne antistatic coating

1.
1 Antistatic agent (ASA) type

ASA uses ion conduction or hygroscopicity of ions or polar groups in the molecular structure to achieve the electrostatic protection effect
of the coating by directly coating or compounding with the polymer material on the surface of the polymer matrix material.
As a surfactant, it can be basically divided into cationic, anionic, zwitterionic and non-ionic types
.
The antistatic agents of small molecules such as alkyl quaternary ammonium salts, alkyl sulfonates, ethoxylated aliphatic alkyl amines, amphoteric imidazoline salts have poor stability and durability, and nonionic ASAs represented by polyethylene oxide alkyl amines or their esters, polyol fatty acid esters, etc.
have poor
compatibility with water systems 。 Therefore, the current research focuses in this direction include: developing new compounds or innovative processes to improve the compatibility of ASA and polymer substrates or water systems, weakening the dependence of coating conductivity on environmental humidity, or inhibiting the migration and loss of small molecule ASA during use.
Add cationic, anionic, etc.
to the non-ionic form to develop complex ASA; Hydrophilic polymer ASA with permanent efficacy is developed by using block copolymerization and other technologies to achieve synergy
with polymer system and aqueous compatibility, processability, thermal stability, mechanical stability, moisture resistance, etc.
For the complex mixing system, it is necessary to pay attention to the matching between different types of ASAs; For polymer ASA, attention needs to be paid to reducing the technical threshold, reducing the amount of addition and controlling the cost
.

Lu Zhikai et al.
prepared waterborne antistatic coatings
by using transparent waterborne polyurethane (WPU) as the matrix resin, and compounding with modified polystyrene sulfonic acid (PSS) and new quaternary ammonium salt BT-12.
The conductive mechanism of the coating is: the hydrophilic group in the molecular chain segment of the modified PSS migration to the surface of the coating can absorb moisture; Quaternary ammonium salts are easy to form a network or layered conductive network on the surface of the polymer, and its ions are easy to aggregate in the system to form chemical cross-linking points, which can greatly improve the antistatic performance
.
The coating has good mechanical properties on polyethylene terephthalate (PET) substrate, light transmittance ≥ 80%, haze ≤ 10%, which can not only meet the requirements of medical imaging film, but also show good antistatic properties
at low humidity.

However, ASA molecules usually have the disadvantage
that they are easily lost from the surface of the antistatic coating and the effect is not durable enough.
Wen Annan synthesized prepolymers with maleic anhydride, phthalic anhydride, polyethanol-400, propylene glycol, butylene glycol, etc.
, and then prepared a waterborne antistatic coating that could be cured by ultraviolet light by forming a salt with NaOH, in which acrylonitrile was used as a crosslinking agent and acryloylisoethyl phosphate with double bonds was used as ASA
.
The polymerization reaction initiated by ultraviolet light can bond ASA to the resin, overcome the shortcomings of easy loss of ASA in the coating, and improve the aging resistance
of the coating.

1.
2 Conductive packing type

1.
2.
1 Metals and their oxides

Conductive adhesives prepared from epoxy resins and metallic silver nanopowders marked the beginning
of conductive coatings.
Due to the small environmental impact of antistatic properties and enhanced mechanical properties, waterborne antistatic coatings prepared by nanometals and their oxide powders as conductive fillers are still one of the focuses of research in the field of
conductive coatings 。 Compared with traditional metal fillers such as silver powder, copper powder, zinc powder, nickel powder and its alloy powder, the focus of current research is on metal oxide semiconductor fillers with lower development costs, better environmental stability, better corrosion resistance, better transparency and lighter color, such as titanium oxide (TiO2), tin oxide (SnO2), antimony oxide (Sb2O3), zirconia (ZrO2), antimony tin dioxide, etc
.
However, these inorganic nano powder fillers generally have problems such as
poor compatibility with polymer matrix materials and water, poor dispersion, easy settlement during coating storage, easy to fall off after use, and not easy to color.
Therefore, the modification of metal oxide semiconductors is a solution strategy that the academic community is more concerned about
.

Luo Xiaomin et al.
added nano-TiO2 powder modified on the surface of silane coupling agent KH-550 to polyurethane prepolymer to prepare modified TiO2/WPU waterborne antistatic coating, and used it as a film-forming substance to prepare microfiber synthetic leather
.
The addition of modified TiO2 can give WPU antistatic properties, while improving its wear resistance, folding resistance, water resistance, weather resistance, bonding, stain resistance and thermal stability, without affecting the surface flatness
.
At the same time, the fiber structure provides rich micropores, which significantly improves the breathability and vapor permeability of the leather surface
.

Yousefi et al.
prepared modified ZrO2/WBPU waterborne antistatic coatings
by compounding (3-aminopropyl)triethoxysilane surface modified nano-ZrO2 powder with acrylic polyol monomer and hydrophilic isocyanate prepolymer by using sol-gel process.
The modified ZrO2 nanopowder can covalently crosslink with the resin matrix to form a stable and uniformly distributed hybrid bonding composite coating, which can significantly improve the bonding strength, increase the surface roughness, and avoid dust adsorption
on the surface while giving the coating antistatic properties.

Sun et al.
used SnCl4 and SbCl3·5H2O as raw materials, successively through solid-liquid heterogeneous co-precipitation reaction, zirconium beads in deionized water grinding, nano-doped antimony-doped tin dioxide aqueous dispersion, which was sheared and emulsified with WPU at high speed, and a transparent antistatic coating
was prepared by drying.
Its light transmittance on PET substrate ≥ 80%, the surface resistivity is about 105 Ω, and the mechanical properties are good
.

1.
2.
2 Carbon-based materials

Compared with metals and their oxide materials, carbon materials such as conductive carbon black (CB), graphite, carbon nanotubes (CNT), and graphene have the advantages of abundant sources, low cost and good corrosion resistance, so antistatic coatings with conductive fillers are also widely
used 。 Among them, carbon black and graphite have advantages in terms of raw material sources and costs, but in the field of waterborne antistatic coatings, the application of CNT and graphene is the mainstay, thanks to their water dispersibility can be improved by structural or surface modification, less amount is added in the polymer matrix material, and the conductivity and mechanical properties of the coating are more excellent, and it has rich optical, electrical, magnetic, catalytic and other properties
.
However, the color, easy flocculation and insufficient compatibility with polymer matrix materials of such fillers are still problems that need to be overcome

Li Hui et al.
added the modified CNT to the well-mixed water-based epoxy (WEP)/curing agent in the ultrasonic state to prepare CNT/WEP antistatic coating
.
The surface resistance of the coating has been reduced by 3 orders of magnitude, reaching the antistatic requirements, and the adhesion and impact resistance have been improved
.

Tian et al.
used TX-100, an emulsifier and dispersant, to achieve uniform dispersion
of single-walled carbon nanotubes (SWCNTs) in water.
The surface resistivity of the coating on PET substrate is between 102~105 Ω, with high optical transmittance (>80%), strong adhesion, and excellent
water and heat resistance.

Graphene oxide (GO) has excellent electronic conductivity, mechanical and aging resistance, and a small amount of addition can effectively improve the conductivity, impact resistance and aging resistance
of polymer materials.
Hu Nan et al.
prepared waterborne antistatic coatings
by mixing the dispersion of aqueous acrylate, GO and wetting agent with curing agent, amino resin, alcohol and ether solvent.
The presence of surface modification groups makes the dispersion effect of GO in the resin better, and the volume resistivity of the coating is 2.
6×107 Ω·cm, with antistatic application potential
.

1.
2.
3 Conductive polymers (CPs)

Compared with inorganic metal or carbon-based fillers, CPs have the advantages of easy processing, light weight, and controllable conductivity, which can not only be blended with water-based resins as organic conductive fillers, but also as film-forming substances at the same time, and water-based antistatic coatings
can be directly prepared without the need for polymer matrix materials.
In addition, as an intrinsically conductive polymer with rich structure and light, electricity, magnetism, force, catalysis and other characteristics, it is easy to achieve the synergy
of coating antistatic and anti-corrosion, electromagnetic shielding, sterilization and other functions.
At present, the CPs used in the field of waterborne antistatic coatings mainly include polyaniline (PANI) and poly(3,4-ethyldioxythiophene)/polystyrene sulfonic acid (PEDOT/PSS) (Figure 2).

This is mainly due to the low cost and aqueous processability of PANI, as well as the special advantages
of PEDOT/PSS itself as a commercial aqueous dispersion.

PEDOT/PSS, as one of the most deeply researched and widely used waterborne CPs, was originally developed based on the application requirements of film antistatic applications, and is generally prepared
by the oxidation of 3,4-ethyldioxythiophene (EDOT) in sodium polystyrene sulfonate (PSSNa) PSS aqueous emulsion by ferric p-toluenesulfonate or sodium persulfate/ferrous sulfate.
Karri et al.
prepared PEDOT/PSS aqueous dispersion with benzoyl peroxide as oxidant, and its coating had good adhesion and flexibility in L-type folds, transparent sheets and glass plates, and the surface resistivity was in the antistatic range
.
However, PEDOT/PSS coating is easy to absorb moisture and has poor
water resistance due to the presence of a large number of hydrophilic groups in the PSS molecular chain.
Cai et al.
prepared poly(sodium p-styrene sulfonate-co-sodium acrylate) (PSA) by copolymerization of sodium acrylate and sodium p-styrene sulfonate monomer, and instead of PSS and 3,4-ethyldioxythiophene chemical oxidation polymerization to obtain PEDOT/PSA aqueous dispersion
.
Compared with PEDOT/PSS, PEDOT/PSA coating on PET substrate achieves better water resistance when the surface resistivity (1.
5×104 Ω) and light transmittance are comparable, and can be used
as a waterborne antistatic coating itself.

Although PANI is very cheap compared to PEDOT/PSS and the source and preparation of raw materials are easier, the thermal stability is slightly poor, and aniline carcinogens may be decomposed, and the stability and compatibility between polymer matrix materials such as PANI and WPU are also major challenges
for its application.
Wang et al.
prepared nano-PANI-SWPU aqueous dispersion
by chemical grafting polymerization using anionic-nonionic sulfonated waterborne polyurethane (SWPU) as polymer matrix material.
By improving the compatibility between PANI and polyurethane, the storage stability
of the aqueous dispersion of more than 1a is achieved.
Moreover, the processing capacity and thermal stability of PANI doped with sulfonated groups are superior to PANI, and the coating can be directly applied
as an antistatic coating.

1.
2.
4 Composite conductive materials

In order to make up for the shortcomings of a single conductive filler, the development of composite conductive filler system by using the advantages of different conductive fillers has received more and more attention in the field of waterborne antistatic coatings, especially in the composite of graphene materials and CPs or polymer compounds, as well as the composite of inorganic metal oxides and CPs
.

Zhang Chandong et al.
first prepared a stably dispersed reduced graphene oxide (rGO) in the aqueous phase by ultrasonic dispersion of GO under the action of hydrazine hydrate, and then prepared polypyrrole (PPy)/rGO composite conductive materials
with cetyltrimethylammonium bromide (CTAB) as template agent, rGO as dopant, pyrrole as monomer, and FeCl3·6H2O as polymerization initiator 。 The addition of CTAB makes PPy easier to form a regular linear structure that constitutes a conductive channel, and plays a doping role conducive to charge transfer, so that the composite has higher thermal stability and conductivity than PPy, so that the composite coating formed with WPU can obtain good antistatic properties
when the amount of addition is small.

Jiang et al.
prepared polyimide (PI) @GO microspheres with core-shell structure by coating method, and then prepared water-based antistatic coatings by blending with ammonium polyaminate salt and CNT aqueous solution
.
PI@rGO microspheres can be attached to the CNT to form a three-dimensional conductive network, so that the volume resistivity of the coating is reduced by 5 orders of magnitude from PI/CNT to 6.
6 ×105 Ω·cm, not only presents good antistatic properties, but also has good mechanical properties and thermal stability
.

Nguyen et al.
prepared PANI/SiO2 composite conductive materials by in-situ chemical oxidative polymerization, and prepared antistatic coatings
by mechanical stirring mixed with WEP.
17.
The addition of PANI/SiO2 with a 2% SiO2 content significantly improves the mechanical properties (abrasion and impact resistance)
of the coating.
The surface resistivity and volume resistivity of the coating are 1.
3×1011Ω and 6.
6×1010Ω·cm, respectively, and have antistatic application potential
.

Chen et al.
synthesized core-shell PANIDBSA/χ-Al2O3 nanoconductive composites by in-situ polymerization using dodecylbenzenesulfonic acid (DBSA) as dopant and surfactant, and prepared WPU/PANI-DBSA/χ-Al2O3 coating
after blending and curing with WPU.
The introduction of χ-Al2O3 nanosheets significantly enhances the mechanical properties of the WPU matrix, and the coating has excellent antistatic properties, and the surface resistivity can be as low as 1.
5×104Ω
.

In general, the composite conductive material waterborne antistatic coating not only has good antistatic performance, but also thanks to the addition of carbon materials and metal oxides, its coating generally has high thermal stability and mechanical properties, which enhances its practical application ability
.

2 Multifunctional waterborne antistatic coating

Giving antistatic coatings hydrophobic, antibacterial, anticorrosive and other functions helps to expand the application range of waterborne antistatic coatings, or better meet the actual application needs
of specific situations.

2.
1 Hydrophobic/superhydrophobic

The hydrophobic properties of the antistatic coating can be imparted or improved by increasing the roughness of the coating surface or reducing its surface energy
.
Liang et al.
used hydroxyethyl methacrylate to chemically combine polyacrylate with WPU into waterborne polyurethane-acrylate (WPUA) latex, and then added and mixed the N-methylpyrrolidone dispersion of PANI to obtain WPUA/PANI emulsion with good stability
.
Compared with WPU, the introduction of interfacial hydrogen bonds increases the interaction force between WPUA molecular chains, effectively improves the water, heat resistance and mechanical properties of its coating, and exhibits better antistatic and hydrophobic properties
.

Traditional WPU coatings are difficult to apply to hydrophobic coatings due to their poor conductivity, wear resistance and corrosion resistance
.
Wang et al.
added hydrophobic polytetrafluoroethylene (PTFE) emulsions and multi-walled carbon nanotubes (MWCNTs) to WPU, and used the synergy of the low surface energy of PTFE and the micro-rough structure of MWCNTs to prepare MWCNTs/WPU superhydrophobic conductive coatings
with microrough surfaces on steel substrates by electrostatic spraying.
In addition, the addition of PTFE also reduces the friction coefficient of the coating and improves its wear resistance
.
When the mass ratio of WPU, PTFE and MWCNTs is 7:3:0.
2
.
When the coating has the best structure and composite properties.

Xu et al.
prepared a multifunctional microcapsule with paraffin as the core material, polystyrene (PS)/silane coupling agent modified GO (γ-GO) as the shell by Pickering emulsion polymerization method, and obtained paraffin @PS/Rγ-GO phase change microcapsule by ascorbic acid reduction, and then mixed with water-based silicone resin and poured on the fabric, using the micro-nano structure bulge formed by the microcapsule on the surface to obtain a multifunctional (conductive, superhydrophobic, energy storage) fabric coating, which can be used for outdoor sports, Special protection
in medical fields and other fields.

2.
2 Antibacterial/bactericidal

Waterborne antistatic coatings with antibacterial properties have important application value
in operating rooms, medical equipment production workshops, schools and other places with special needs for sterilization.
At present, the main means adopted is to delicately design the composition and structure of the conductive filler, giving it and giving it multiple functions
.

Mirmohseni et al.
synthesized PANI/rGO+ nanohybrids by in situ interface polymerization, and then incorporated into WPU matrix to obtain waterborne antistatic coatings
.
Surface resistivity of coatings as low as 9.
8×106 Ω and exhibits antimicrobial activity
against gram-positive and gram-negative bacteria.
Among them, the tip structure of rGO+ nanosheets, as well as the quaternary amine and amide groups contained in them, and the positive charge of doped PANI nanofibers are the reasons
for killing bacteria and affecting their growth, respectively.
In addition, the research group [26] also developed Cu/reduced monolayer graphene oxide (Cu/rSLGO) nanohybrids by in situ reduction, using rSLGO nanosheets to cause physical damage on bacterial membranes, the contact effect of Cu nanoparticles and the synergistic effect of Cu2+ ions released by Cu/rSLGO to inactivate bacteria, and achieve efficient inactivation
of Staphylococcus aureus and Escherichia coli 。 In addition, the addition of 3.
0% Cu/rSLGO can form sufficient conductive pathways in the WPU matrix, giving the modified WPU coating antistatic properties, and the surface resistivity reaches 4.
8×109 Ω
。 Similar functions are seen in
WPU waterborne coatings compounded with PANI-Cu@ZnO nanohybrids.
At the same time, PANI-Cu@ZnO also improves the adhesion of WPU coatings and enhances scratch resistance
.

2.
3 Antiseptic

Carbon-based materials such as CPs represented by PANI, rGO, MWCNTs not only have electrical conductivity, but also help to enhance the corrosion resistance of polymer matrix materials, so as to realize the dual functions
of antistatic and anti-corrosion of coatings.

Zhao et al.
synthesized PANI/rGO
with good thermal stability, electrical conductivity and water dispersibility by one-pot emulsion polymerization.
Water-based coatings with antistatic and anti-corrosion functions were prepared in combination with WEP, and the surface resistivity of the coating could reach 2.
5×108 Ω
。

Zhang et al.
prepared WPU/polydopamine (PDA) functionalized rGO (WPU/PDrGO) nanomaterials
by in situ emulsification.
The existence of the interface PDA layer is not only conducive to the dispersion of PDrGO sheet in the WPU matrix, but also can strengthen, harden and toughen the matrix, which is expected to be used in
anti-corrosion, antistatic and other fields.

Wang et al.
prepared a reduced graphene oxide-coated functionalized silica hybrid (f-SiO2@rGO) by electrostatic assembly and sodium borohydride reduction with the assistance of silane coupling agent, and then uniformly dispersed it with antimony-doped tin dioxide (ATO) in WEP to prepare ATO+f-SiO2@rGO/WEP coating
.
Thanks to its special structure, the coating exhibits enhanced anti-corrosion and antistatic properties, surface resistivity2.
2×106 Ω
。

Wang et al.
developed WPU-based antistatic coatings with MWCNTs gradient distribution of "low content-high content-low content-high content", which showed good adhesion, anti-corrosion and antistatic properties
.
The Q235 steel coated by it still showed good corrosion
resistance after soaking in 40 °C, 3.
5% NaCl solution for 29 days.

2.
4 Other Features

Waterborne antistatic coatings can also be introduced into emerging materials such as MXene or coated on flexible materials such as leather and textiles to achieve the needs
of photothermal conversion, noise reduction, wear resistance, flexibility, toughening and other functions.

Taking advantage of MXene's excellent electrical conductivity, efficient photothermal conversion, excellent compatibility with waterborne polymers and surface activity, Wei et al.
prepared MXene/polyacrylate waterborne antistatic coatings
by mixing MXene with aqueous polyacrylates by solution method.
Its surface resistivity of leather surface coating can reach 7.
9×109 Ω, and exhibits enhanced mechanical properties and excellent photothermal conversion ability
.
The surface temperature of leather after 5 min of 275 W infrared light is 46 higher than that of pure polyacrylate coating.
At 9 °C, the surface temperature after 30 min of sunlight exposure was 5 higher than that of polyacrylate coating.
4 °C, can be applied to winter antistatic and self-heating outdoor clothing
.

Tang et al.
prepared water-based antistatic coatings from WPU, graphite nanosheets and sodium lauryl sulfate, and then deposited on the surface of non-woven fabrics by dipping method, which not only obtained a surface resistivity of about 108 Ω, but also made its acoustic transmission loss from 3.
The 87 dB has been increased to more than 18 dB, showing good noise reduction effect, and can withstand more than 2000 times of grinding wheel wear, and the wear resistance is greatly improved
.

3 Biomass-replaced waterborne antistatic coatings

With the deepening of the concepts of green chemistry and environmental protection "zero emission", the research on the partial or complete replacement of fossil raw materials with biodegradable or renewable biomass materials has received more and more attention
.
In the field of waterborne antistatic coatings, at present, strategies such as the preparation of bio-based waterborne resin matrix materials by modifying conductive fillers with biomass components are mainly adopted
.

Seyed Shahabadi et al.
prepared lignin non-covalently modified graphene (LMG) and added it to WPU to prepare WPU/LMG waterborne conductive coatings
.
Its coating not only has antistatic ability, but also shows comprehensive performance
such as energy storage, photothermal conversion, and infrared repair.

Gurunathan et al.
synthesized castor oil-based waterborne polyurethane (COWPU)/PANI waterborne antistatic coatings
.
PANI can not only be well dispersed in COWPU to form a uniform conductive pathway, but also its intramolecular —NH bond can form a significant hydrogen bond with COWPU's —C=O bond, thereby improving the thermal stability
of the coating.

Dai et al.
first prepared modified castor oil (MCO) by thiol-ene click chemical reaction between castor oil and 3-mercaptopropyltrimethoxysilane, and then introduced it as a bio-based polyol into the synthesis of ultraviolet curable WPU, and prepared MCO-modified WPU coating
.
MCO improves the surface hydrophobicity and water resistance of
WPU coatings.
An antistatic coating
can be prepared by adding conductive carbon black (CB) and mixing well.

Liu et al.
prepared poly(tannin carbamate) (PTU) by the gradual polymerization of biomass tannins and toluene diisocyanate; It was used as a dispersant for MWCNTs, and PTU-stabilized MWCNT/CB/PTU aqueous dispersion was obtained by ultrasonic and homogenization treatment.
Next, waterborne antistatic coatings MWCNTs/cb/ppu/wpu
were prepared by mixing with WPU.
Its coating on the surface of polyvinyl chloride substrate, the surface resistivity can be in the range of 104~108 Ω, and the adhesion can reach 0.

4 Conclusion

Waterborne antistatic coatings have developed major general-purpose systems such as antistatic dosage forms and conductive filler types, and are moving
towards multi-functionality and bio-based substitution.
With the deepening of relevant research, they have shown important practical value
in industrial production, construction industry, electronics industry, aviation and military industry.
However, its subsequent development still faces some difficulties and problems
.
For example, the preparation or coating process of some coatings is cumbersome, which restricts their large-scale production and construction; Some coatings still use expensive and corrosive metal fillers; The dosage of polymer antistatic agent is large and the cost is high; The stability of composite coatings and the compatibility between components are still insufficient; Most coatings are difficult to recycle or degrade.

In addition, the measurement of the antistatic performance of conductive coatings usually requires comprehensive testing of its volume resistivity, surface resistivity and electrostatic attenuation rate, but most of the literature stays on the characterization of the first two, and cannot answer the needs
of comprehensive performance indicators such as low electrostatic attenuation rate in practical applications such as industrial manufacturing and medical protective fabrics.
Therefore, in the future, all-organic coatings based on CPs and all-bio-based coatings prepared from degradable and renewable resources such as biomass compounds will be the directions
that need to be focused on in this field.
At the same time, special coatings and multi-functional coatings that adapt to the needs of specific scenarios will also be the direction of urgent development in
this field.
How to use the technology, design concept and experience in the cross-cutting field to improve the application effect of waterborne conductive coatings in existing fields, and promote their application in emerging scenarios such as 3D printing products, wearable electronic products, flexible or stretchable electronic products, self-healing coatings, etc.
, is also necessary to invest more research resources
.
In addition, how to continuously reduce the production and construction costs of coatings, and achieve the comprehensive evaluation of many performance indicators of anti-static coatings, is also a core factor
that must be considered in practical application and promotion.