Anti-corrosion coatings are an important variety of coatings.
Affected by factors such as restrictions on volatile organic substances (VOC) and hazardous air pollutants (HAPs) by petroleum resources and environmental protection regulations, the anti-corrosion coating industry is rapidly developing in the direction of "greening" while continuously improving its performance.
Based on the principles of pollution-free, pollution-free, energy-saving, and economical efficiency, paint workers develop paint varieties that are pollution-free or less pollution-free and have excellent anti-corrosion properties.
Pollution-free overall design of anti-corrosion coating technologyPollution-free overall design of anti-corrosion coating technology
The so-called pollution-free overall design of anti-corrosion coating technology means that the various components of the coating itself (film-forming substances, anti-corrosion pigments, solvents and auxiliaries), the synthesis of raw materials, the coating production process, and the pretreatment of the substrate should be considered during the research and development.
The overall pollution-free process, construction process, etc.
For example, although the raw materials used are pollution-free by themselves, their production process does not meet environmental protection requirements and must be discarded, such as chlorinated rubber; some materials, such as Hongdan antirust paint, have excellent performance, but they are poisonous and harmful.
Human beings are not safe and easy to cause environmental pollution, so even if its performance is good, it cannot be used; in order to use anti-corrosion coatings on metal surfaces, pretreatments such as degreasing and rust removal must be carried out first, and the pretreatment process generally pollutes the environment.
And the cost is relatively high.
If rusty paint is used, direct coating on the surface of rusty steel can stabilize, passivate or transform the rust; in order to reduce the environmental pollution of the pretreatment process, a pollution-free sandblasting and rust removal process has also appeared.
, Such as wet sandblasting technology.
In this regard, it is very important to break through traditional concepts.
Pollution-free or low-pollution water-based, high-solid, solvent-free and powder anticorrosive coatingsPollution-free or low-pollution water-based, high-solid, solvent-free and powder anticorrosive coatings
Water-based anticorrosive coatings: Inorganic zinc-rich coatings are an important variety of water-based anticorrosive coatings.
They are mainly used as primers and have excellent anticorrosive properties.
The developed zinc-rich paint contains 95% zinc, has been used for many years, and has excellent anti-corrosion properties.
The water-based high-modulus potassium silicate and lithium zinc-rich coatings developed in China in recent years have been applied in engineering, and their performance has been continuously improved.
As a zero-VOC environmentally friendly anticorrosive coating, it has been accepted by all walks of life.
In recent years, water-based rusty composite anti-rust paints, water-based rusty emulsion type anti-rust paints, bottom-side water-based rusty anti-rust composite paints, etc.
have also appeared, which can be used on steel substrates with imperfect rust removal.
When applied underwater, these coatings can form a very durable protective system when combined with appropriate water-based or high-solid topcoats.
Ocean Chemical Research Institute adopts core-shell structure and self-emulsifying polymer emulsion manufacturing technology to develop nano-scale water-based acrylic modified alkyd latex, nano-scale water-based amino acrylic modified alkyd latex, water-based epoxy acrylic amino micro-latex, and these A series of water-based anticorrosive coatings prepared by latex have been used for anticorrosion in petrochemical, metallurgy, Wujinjiaodian, automobiles, rolling stock, trucks, ships and other fields.
Water-based coatings are more dependent on the construction environment.
How to ensure that good performance coatings are obtained in high humidity, low temperature and closed environments is a problem that water-based anti-corrosion coatings need to solve in the future.
Solvent-free and high-solid coatings with a volume solid content of 60% or a mass solid content of 80% or more are called high-solid coatings.
With the increasing requirements for environmental protection, high-solid coatings have become an ultra-fast, ultra-wide application variety in low-pollution coatings in recent years.
At present, there is a trend toward 100% solid content, that is, solvent-free coatings.
Solvent-free paint, also known as active solvent paint, is a paint made of synthetic resin, curing agent and active solvent.
All components in the formulation system, except for a small amount of volatilization, participate in the reaction to cure and form a film, which will pollute the environment.
Less, solvent-free systems usually have higher viscosity and require special construction tools and techniques, which are still under development.
Spray Polyurea Elastomer Technology (SPUA) is a new solvent-free and pollution-free spray construction technology developed abroad in recent years to meet the requirements of environmental protection.
At present, there are also corresponding systems developed in China.
It is a promising anti-corrosion technology.
Powder coating: Powder coating is a kind of energy-saving, resource-saving, low-pollution coating, its utilization rate is as high as 95-99%, and it has developed rapidly in recent years.
Epoxy powder coatings are commonly used in anti-corrosion engineering.
Epoxy powder coating for pipeline anticorrosion is a new type of coating that is completely solvent-free, sprayed in powder form and melted into a film.
The current problem is that the impact resistance and hygroscopicity need to be improved and improved.
Domestically produced pipeline anticorrosive epoxy powder coatings still have a certain gap in storage stability and coating workability compared with foreign high-quality products.
Epoxy powder coating is a variety of anti-corrosion coatings for new pipeline anti-corrosion projects.
The application of low-temperature curing resins is becoming more and more popular, and the durability of super weather-resistant resins has been further improved.
Hybrid new varieties such as polyester/acrylic powder coatings have appeared, and fluororesin powder coatings with super weather resistance and super durability have been developed.
Polyisocyanate-cured hydroxy fluorine resin powder coating under curing conditions of ~200°C/20 minutes.
Regarding the use of curing agents, Europe and the United States have gradually eliminated the use of toxic TGIC (triglycidyl isocyanate) in recent years, and switched to hydroxyalkane in amides.
At present, the main research direction in this area is to develop a process that can increase the construction speed and how to reduce the thickness of the coating film.
Reducing the particle size and improving the reaction activity are the keys to reducing the coating film thickness and increasing the construction speed.
High performance and multifunctionality of anticorrosive coatingsHigh performance and multifunctionality of anticorrosive coatings
Silicone modified polyurethane, organic fluorine modified polyurethane coatings, fluororesin coatings and other high-performance coatings are another important aspect of the development of anticorrosive coatings.
The development trend is that the demand for long-life anti-corrosion coatings will increase, requiring 10 years or even more than 15 years, and it is suitable for very harsh corrosive environments; the anti-fouling life of anti-fouling coatings is more than 5 years.
Multifunctional anti-corrosion coatings will also develop rapidly, such as solar shielding anti-corrosion coatings, damping anti-corrosion coatings, weather-resistant and anti-corrosion polyurethane coatings, peelable anti-corrosion coatings, flame-retardant static conductive, temperature-resistant and anti-corrosion coatings.
Pollution-free anticorrosive pigmentPollution-free anticorrosive pigment
Passivation or corrosion-inhibiting heavy-duty anti-corrosion coatings generally use the development direction of anti-corrosion coatings containing heavy metals such as chromium and lead.
Nano particles such as nano-sized TiO2, ZnO, CaCO3 and SiO2 have excellent synergistic effects when used in anti-corrosion coatings.
Due to the high surface energy of nanoparticles, they are easy to combine with other atoms, which increases the compactness of the coating and the resistance to ion penetration.
In addition, it can also improve the rheology of the coating, improve the adhesion of the coating, the hardness of the coating film, the smoothness and the anti-aging performance, which is one of the important development directions.
Development of anti-corrosion primer for low treatment surfaceDevelopment of anti-corrosion primer for low treatment surface
In the anti-corrosion project, the construction cost accounts for more than 70%, and the surface treatment (rust prevention, oil removal, etc.
) based on sandblasting accounts for more than 70%.
At the same time, under many on-site construction conditions, it is impossible to reach the standard of sandblasting Sa2.
5 or higher, so it is applicable to low-treated surfaces-lower than Sa2 grade, with moisture or oil (oil tank maintenance).
The paint puts high demands on.
Strengthen the integrated quality management system of paint and paintingStrengthen the integrated quality management system of paint and painting
A complete coating technology development, construction and service management system is the basic guarantee for achieving the expected anti-corrosion goals.
The establishment and improvement of a procedural coating development and production process management, qualified personnel training and certification management, and the establishment and improvement of the management system of the coating site are huge challenges facing the field of anti-corrosion coatings in my country.