Fluorocarbon Coatings Have Bright Application Prospects   

Every year, the economic loss caused by the corrosion of steel, iron and other metal equipment in the world is expected to reach up to US$700 billion. Therefore, the corrosion protection of metal equipment is very important.
   As a classic protective method, coatings have been widely used to protect metal equipment. In many occasions, a layer of coating is often composed of the primer, intermediate paint and finish. For the protection system of steel and iron equipment, the primer is generally zinc-rich primer or epoxy primer, and the intermediate paint is usually epoxy micaceous iron oxide paint or epoxy glass-flake paint. The resins used for the finish can be divided into three grades: low, intermediate and high grades. Low-grade resins include epoxy resin, chlorinated rubber and chlorosulfonated polyethylene; intermediate grade ones include polyurethane; and high-grade ones include silicone modified polyurethane, silicone modified acrylic resin, and fluorocarbon resin. The three high-grade coatings for key anti-corrosion coating projects are polyurethane, fluorocarbon and polysiloxane. In recent years, because of its superior performances, fluorocarbon resin has been widely used for coatings.
   Fluorocarbon resin features strong F-C bond, small polarity, low cohesive energy, high chemical inertness and good temperature resistance. Among all types of resin, fluorocarbon resin has the lowest critical surface tension. Because of its special molecular structure, fluorocarbon resin has many excellent performances: super-high weather resistance, low surface energy (high hydrophobicity), low friction coefficient (high lubricity), excellent chemical resistance and corrosion resistance, making fluorocarbon resin become the preferred choice for the finish of a variety of composite coatings.
   Now, fluorocarbon coatings have been widely used in high-end buildings, petrochemical facilities, marine projects and many other areas. Fluorocarbon resins for coatings mainly include polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE) and chlorotrifluoroethylene - vinyl ether (FEVE). FEVE coatings have better workability and overcome the drawbacks of PVDF, PTFE coatings in construction. In addition, FEVE coatings have excellent weather resistance and corrosion resistance and are especially used as the weather-resistant finish of long-acting anti-corrosion coating systems.

1  Applications in high-end buildings

Due to their excellent weather resistance, fluorocarbon coatings have become the preferred choice for the outer coatings of high-end buildings and widely used in the decorative and protective coatings of a variety of landmarks, large buildings, bridges, airports and railway stations. For example, Japan's Tokyo Bay Bridge uses the fluorocarbon coating as the finish of its composite coating system. After the bridge coatings last for 20 years, the coatings are still intact. China's Hangzhou Bay Bridge, one of the world's longest cross-sea bridge, uses the FEVE fluorocarbon coating as the finish of its protective coating system. This choice is based on relevant scientific environment testing and research and domestic and international experiences in construction. The "Bird's Nest", a landmark building of the 2008 Beijing Olympics, is also painted with fluorocarbon coatings, having a total coating area of 284 000 square meters.

2 Applications in petrochemical facilities

Fluorocarbon coatings have also been widely used in the petrochemical industry. With the rapid development of the petrochemical industry, the number of oil tanks and oil and gas pipelines are increasing fast. These facilities need long-lasting coatings and also require that the coatings have strong anti-static capability and high corrosion resistance and weather resistance in a variety of conditions. To meet these requirements, researchers have developed a type of conductive fluorocarbon coatings, which are made by formulating Daikin's CK curing fluorine resin with some conductive carbon black and other agents. This meets petrochemical enterprises' demand for long-term anti-corrosion coatings and plays an important role in the development of the petrochemical industry.

3  Applications in fasteners

Fasteners used in marine engineering are more prone to corrosion due to high moisture and high salt spray environments. And the harsh marine environment can often result in fasteners to rust, making fasters more difficult to be dismantled, and increasing maintenance costs. In addition, the mechanical performance decline and even rupture of fasteners caused by corrosion can lead to equipment paralysis and even accidents. Therefore, how to choose proper composite coatings for fasteners to prolong their life-span in the marine conditions has become an issue urgently to solve.
   Due to their good weather resistance and lubricity, fluorocarbon coatings now begin to be applied onto fasteners and other parts in engineering projects. For example, the United States' Stand Cote's SC-I fasteners are painted with fluorocarbon coatings. Such fasteners can be applied to a variety of conditions (including the marine condition), having excellent corrosion resistance, wear resistance, lubricity and anti-bitten performance. Salt spray tests at 43 degrees centigrade how that the coatings are intact after 720 hours and their appearance is much better than zinc-plating and cadmium-plating layers. Take another example. TiBi Coat 35 coating and TiBi Coat 47 coating are composed of lubricating fluorocarbon resin, special fluorocarbon resin and special resin adhesives. The two types of coatings have very strong binding force with various metal substrates. TiBi Coat 35 coating has ideal protective performance in the brine medium (or the marine environment) in moderately stringent conditions and a low friction coefficient, but cannot resist alkali, and its working temperature cannot exceed 300 degrees centigrade. TiBi Coat 47 coating is suitable for corrosive environments (including the marine environment) in moderately stringent conditions and has excellent anti-injury capacity and lubricity. It is resistant to acids, alkali and solvents and is a good protective coating for fasteners, but its working temperature cannot exceed 165 degrees centigrade.

   FEVE has excellent weather resistance and corrosion resistance. And it has shorter curing time than other fluorocarbon resins, greatly shortening the construction period. In addition, new-type water-based FEVE coatings have low VOC emissions and are harmless to the human body, so they are environmentally friendly coatings. Therefore, FEVE will have wider applications as the finish of composite coatings for fasters used in marine engineering projects.