PTFE Coating Selection
The selection of the correct grade of P.T.F.E. is important for the best performance results. Industrial coatings can be applied to steels, alloys, brass, aluminium and special materials such as Inconel. Elastomers and plastics are also included as suitable substrates to be coated. For optimum adhesion, the substrate requires abrading to secure good bond between the PTFE and the product.
When discussing PTFE coatings, the reference is also made to Fluoropolymers. What are fluoropolymers?
Fluoropolymers are a kind of “super plastic” – a high-performance material with unique strength and durability.
Fluoropolymers are probably best known for their use as a coating in non-stick cook- and bakeware, and in the rugged, all-weather apparel favoured by skiers, sportsmen and other enthusiasts of the great outdoors. But fluoropolymers have dozens of other major applications that are essential to modern life, including critical uses in aviation, electronics, telecommunications, automobiles and trucks, pollution control and national security.
Fluoropolymers are relied upon because of their unique properties, including significant chemical and heat resistance and a great ability to withstand corrosion, even in the most challenging environments.
Fluoropolymers are integral to a clean environment, to a globalized and interconnected world, to a vigorous economy, and to the safety and security of the public.
Questions have been raised regarding a few of the chemicals used to make fluoropolymers. These chemicals are not ingredients in fluoropolymers or products made with fluoropolymers, but instead are used as a processing aid at the initial stages of fluoropolymer production.
It is important to note that products made with fluoropolymers are safe. This is supported by decades of research and statements by U.S. and international regulatory agencies – including the U.S. Food and Drug Administration and the European Food Safety Authority – which affirms the safety and reliability of fluoropolymers in their various uses.
Some of the most popular product names within industrial coatings are manufactured to accommodate a wide range of performances.
Teflon®
Xylan®
Emralon®
Excalibur®
The above are registered names for systems within the industry and have the ability to perform different functions, from pure non-stick to outstanding abrasion resistance.
Key attributes of PTFE Coatings
Strength (high strength-to-weight ratio)
Chemical inertness
Biocompatibility
High thermal resistance
High chemical resistance in harsh environments
Low flammability
Low coefficient of friction
Low dielectric constant
Low water adsorption
Good weathering properties
Therefore, industrial coatings can be identified by the following main headings:
1. PTFE
PTFE (polytetrafluoroethylene), providing excellent non-stick properties, these materials have the highest operating temperature of any fluoropolymer and can operate at 260°C and have extremely low coefficient of friction coupled with good abrasion and chemical resistance. These coatings are either single or two-coat systems, comprising of a primer and topcoat and for premium systems three coat systems are available. PTFE is available in aqueous based forms. (View more in Glossary of Terms)
2. FEP
FEP (fluorinated ethylene propylenecopolymer), these materials provide excellent chemical resistance in addition to low friction as well as high performing non-stick properties. Maximum operating temperature is 204°C, however at the cure stage the material melts and flows to produce a nonporous film. FEP is available in both aqueous and powder forms. (View more in Glossary of Terms)
3. PFA
PFA (perfluoroalcoxy), offers the additional benefits of higher in-use continuous temperatures 260°C, coupled with coat thicknesses up to 1,000 micrometers gives greater toughness than PTFE or FEP. PFA also provides good non-stick properties, during the curing stage the PFA coating flows and melts giving a nonporous film. This combination of properties enables PFA to be selected for a wide range of applications, particularly those involving a requirement for chemical resistance. PFA is available in both aqueous and powder forms. (View more in Glossary of Terms)
4. ETFE
ETFE is a copolymer of ethylene and tetrafluoroethylene, although not fully fluorinated, ETFE has excellent chemical resistance and can operate continuously at 149°C. This product can be applied to produce coatings up to 1,000 micrometers, to provide a highly durable finish. The resins within ETFE are the toughest within the fluoropolymer range. ETFE is available in powder form. (View more in Glossary of Terms)
5. One Coat Systems
One coat systems are formulated with special blends of fluoropolymers along with high-performance resins, providing toughness and abrasion resistance. During the cure cycle the coating components stratify and most of the fluoropolymer properties, such as low friction and non-stick, are retained. The resins offer good adhesion and abrasion resistance. These products can be applied to smooth and pre-cleaned substrates.