In recent years, with the rapid economic development, the amount of fluorine-containing resin coatings based on polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluoroalkane alkyl ethyl ether (FEVE) has increased. growth of.
PVDF coatings are mostly used in the field of construction. Various metal plates (aluminum alloy, galvanized steel, stainless steel, prepainted steel coil, etc.) coated with it can be used for exterior walls, roofs, and interior decoration of buildings, and have become an important material to replace ceramic tiles and glass curtains walls.
Definition
Polyvinylidene fluoride (PVDF) is a homopolymer of vinylidene fluoride (VDF), which is a tough engineering thermoplastic.
The alternating distribution of CH2 and CF2 groups in the PVDF molecular chain achieves a unique balance of properties. It not only has the heat-resistant, chemical-resistant, and UV-resistant stability of fluoropolymers but also has the solubility of conventional polymers It also has unique electrical properties such as ferroelectricity, piezoelectricity, and pyroelectricity.
Polyvinylidene fluoride (PVDF) coating is a new type of building material developed in recent years.
PVDF coating can form a protective coating with excellent performance after high-temperature curing. It is an ideal surface protection material. It is widely used in exterior wall decoration of buildings, subways, tunnels, chemical production areas, and other harsh environments for the coating of metal materials.
Process
PVDF fluorocarbon coatings are produced using 70% PVDF resin and 30% acrylic resin, with high-grade weather-resistant pigments (usually inorganic ceramic pigments). It needs to go through a rigorous coating process, and a qualified coating product can be obtained after high-temperature baking and curing.
PVDF fluorocarbon coatings currently on the market include liquid coatings and powder coatings. Most of them are liquid coatings, and there are two main types of coating methods: roller coating and spraying.
Roller-coated fluorocarbon coatings are used for the coating of coiled steel and aluminum coils. Liquid PVDF coatings were developed earlier, with mature technology, and convenient color matching. At present, they are still the main form of fluorocarbon coatings in the world.
PVDF Coating Statistics
| Polyvinylidene Fluoride (PVDF) Coating Statistics | |
|---|---|
| Thickness | .020" - .030" |
| Use Temperature | 500°F Max |
| Chemical Resistance (ASTM D543) | Excellent |
| Abrasion Resistance (ASTM D4060) | Excellent |
| Tensile Strength at Break (ASTM D638) | 6525 psi |
| Coefficient of Friction (ASTM D1894) | .4 Static, .3 Dynamic |
| Dielectric Strength (ASTM D149) | 260 Volts per mil |
| Hardness (ASTM D676) | 80 (shore D) |
Different fluorocarbon coatings
| Types of Product | Painting technology | Property |
|---|---|---|
| Solvent-based fluorocarbon coatings | electrostatic spraying | Weather resistance > 25 A, solvent volatilization |
| Solvent-based fluorocarbon coatings | Roller Coating | The weatherability is greater than 15 A, the utilization rate is higher than that of spraying coating, and there is solvent volatilization |
| fluorocarbon powder paint | electrostatic spraying | No solvent volatilization, environmental protection, high utilization rate, weather resistance more than 15 A |
| Waterborne fluorocarbon coatings | spray coating | Durability, fouling resistance, chemical medium resistance, thermal stability and other excellent properties |
Application
Because PVDF fluorocarbon coating can maintain uniform color and smooth surface for a long time and has excellent resistance to ultraviolet rays, high temperature, humidity, chemical pollution, and other erosion characteristics, it is widely used in construction materials, petroleum engineering, and other fields.
Building materials field
The metal (mainly aluminum and aluminum-plastic panels) decorative panels using PVDF fluorocarbon coatings are colorful, durable, smooth, waterproof and antifouling, sound insulation and shock resistance, heat and cold resistance, lightweight, simple processing, and easy to maintain, easy installation, and other characteristics, become the most important substitute materials for ceramic tiles, clay bricks, and glass curtain walls.
In addition, PVDF fluorocarbon coatings can also be used as coating materials for roofs, doors, and windows, imitation granite, and other decorative objects, and architectural protrusions to protect the color and luster of the decorative objects.
Petroleum Engineering Field
Under the conditions of both temperature requirements and harsh corrosive media or the coexistence of multiple chemicals, such as chemical liquid wastewater tanks, sewage treatment tanks, wastewater treatment system pipelines, storage tanks, and other anti-corrosive coatings, the requirements are very high.
In addition, PVDF has a lower melting temperature and low viscosity, so processability
Good performance can be used for spraying, and can also be used as a whole equipment anti-corrosion lining.
Electronic technology
Because PVDF fluorocarbon coating has a large coating rate and excellent insulation, it is in Europe
The amount of PVDF coatings applied by American Electronics technology accounts for the total consumption of PVDF coatings
1/3, the use of PVDF fluorocarbon coatings can improve the safety of electronic products, product
Quality reliability and service life.
Other areas
In addition to the above application areas, PVDF fluorocarbon coatings can also be used in the food industry
Industry, nuclear power industry, shipbuilding, marine engineering, and other fields.
Advantages and Disadvantages
Advantages
PVDF fluorocarbon coating has the advantages of super weather resistance, non-fading, pollution-free and aging resistance.
Long-lasting anti-corrosion, protection for up to 20 years, longer protection of coated facilities, low maintenance cost.
Contains an F-C chemical bond, strong bond energy, stable molecular chain, strong weather resistance, and the paint film will not powder after long-term use.
Resistant to solvents, acids and alkalis, water, chemicals, and the paint film is intact.
Good decorative appearance, excellent color, and gloss retention, long-term use without loss of gloss, and color.
With self-cleaning characteristics, the paint film is not stained, easy to clean, and last bright as new.
Used in moderate to severely corrosive environments, such as industrial or marine environments.
The painting matching system is very complete, and it can be matched with a variety of coatings.
Disadvantages
The price is high, resulting in high construction costs.
At present, the quality of PVDF Coatings in the market is uneven, shoddy is good, so you need to be cautious when buying, and you should not be greedy for cheap.
The fluorine content in the PVDF Coatings is an important indicator. The fluorine content of the high-quality fluorocarbon paint meets the standard, and the fluorine content of the counterfeit fluorocarbon paint is low or does not contain it.
PVDF finish
PVDF architectural fluorocarbon paint can be divided into three types: plain paint, metallic silver paint, and pearl paint according to the top paint pigment.
According to the coating, it can be divided into four types: two-layer plain paint, three-layer paint metallic paint, two-layer pearl paint, and four-layer pearl paint.
PVDF fluorocarbon coatings are generally divided into three types: primer, topcoat, and finishing paint. Primer is distinguished by resin: there are two types of acrylic series and epoxy series.
The primer is distinguished by color: mainly yellow primer containing strontium chromate, and a small amount of white primer without strontium chromate, but the adhesion effect should be a yellow primer.
PTFE vs PVDF
Performance
1. PTFE: PTFE has the characteristics of high-temperature resistance, and its friction coefficient is extremely low; PTFE has the characteristics of chemical resistance compared with other plastics; PTFE has softer mechanical properties. Has very low surface energy.
2. Polyvinylidene fluoride: It has multiple excellent properties such as elasticity, low weight, low thermal conductivity, high chemical resistance, and heat resistance.
Application
1. Polytetrafluoroethylene: Polytetrafluoroethylene can be formed by compression or extrusion; it can also be made into water dispersion for coating, dipping, or making fibers.
2. Polyvinylidene fluoride: PVDF is often used to make the insulating sheath of wires. Thin 30 gauge wires commonly used in winding circuits and printed circuit boards are commonly used for PVDF insulation. Cables with PVDF insulation are often called “Kynar wires” under the trade name of PVDF.
Liquid PVDF Coatings VS Powder PVDF Coatings
The same composition: use 70% content of PDF resin and high weather resistance inorganic ceramic pigments, and other effective composition.
The same superior performance: It has the same worrying weather resistance and is the best metal overcoat that has been proven so far.
The coating application is different: although they are all high-temperature baking paints, liquid coating uses a liquid coating line and powder coating uses a powder coating line.
Solvent and cost are different: 60-70% of the liquid coating composition is solvent. Liquid paint spraying usually has about 50% of the paint that cannot be used and cannot be recycled.
The powder coating has no solvent and all powders can be recycled. It not only has the characteristics of simplicity, stability, and high efficiency but also saves the cost of solvents, solvent volatilization energy, and environmental protection treatment costs.
Superior performance: Although the weather resistance is exactly the same, the powder coating has the advantages of high hardness, stable production, and small color difference, which can make up for the shortcomings of the insufficient hardness of the liquid fluorocarbon coating on aluminum profiles and other parts.
