Industrial PTFE (polytetrafluoroethylene) Coatings

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has a wide range of useful applications. The best-known brand of PTFE-based formulas is Teflon™ by Chemours. Other popular brands of PTFE are Syncolon by Synco Chemical Corporation or Xylan by Whitford. If you are trying to decide between PTFE, Teflon™ or Syncolon, they are all the same.

PTFE is a fluorocarbon solid consisting entirely of carbon and fluorine. PTFE is hydrophobic which means neither water not water-containing substances can wet PTFE. As a fluorocarbon, PTFE demonstrates mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction of any solid.

PTFE Characteristics

  • Very high melting point: With very high melting point of around 621ºF (327ºC), very few applications will be hot enough to damage PTFE with heat.
  • Hydrophobic: Exceptional resistance to water means PTFE never gets wet, which makes it an ideal coating for cooking, wound dressing and more.
  • Chemically inert: Most solvents and chemicals will not damage PTFE.
  • Low friction coefficient: The coefficient of friction of PTFE is one of the third-lowest of any solid material, which means nothing will stick to its surface.
  • Highly flexible: PTFE can bend and flex, even at low temperatures, so it can be easily applied to various surfaces without losing integrity.

The unique properties of PTFE make it an ideal coating for numerous applications. PTFE is used as a non-stick coating for pans and other cookware. It can provide stain resistance to carpets and fabrics. It is used in nail polish, wiper blades and hair styling tools. PTFE is used to coat the inside of pipes carrying corrosive chemical or very hot substances. Thanks to its inert nature, PTFE is also used in the manufacture human prosthetics because it is unlikely to be rejected by the body.

PTFE is non-reactive, partly because of the strength of carbon-fluorine bonds. For this reason, it is often used in containers and pipework for reacting and corrosive chemicals. Where used as a lubricant, PTFE reduces friction, wear, and energy consumption of machinery. It is commonly used as a graft material in surgical interventions. It is also frequently employed as coating on catheters; this interferes with the ability of bacteria and other infectious agents to adhere to catheters and cause hospital-acquired infections.

PTFE’s coefficient of friction is 0.05 to 0.10, which is the third-lowest of any known solid material. (BAM is the lowest coefficient of friction at 0.02 and diamond-like carbon is the second-lowest at 0.06.) PTFE is so resistant to van der Waals forces insects cannot climb its surface. Unlike an elastomer, PTFE cannot be cross-linked to another polymer. As a result, it has no memory and tends to creep. Because of its superior chemical and thermal properties, PTFE is widely used as a for gaskets for applications that need to resist aggressive chemicals, such as the pharmaceutical and chemical processing industry. Because PTFE tends to creep, Belleville washers are often used to apply continuous for to the PTFE gaskets to minimize performance loss over time.

Applications of PTFE

  • Architectural Membranes. Expanded PTFE (ePTFE), which incorporates a fluoropolymer membrane with micropores, has been used successfully to coat large roofs, such as the Hubert H. Humphrey Metrodome in Minneapolis.
  • Bullets. Certain types of bullets are coated with PTFE to reduce wear on the rifling of firearms.
  • Carbon Fiber and Fiberglass Composites. Most notably for the aerospace industry, PTFE film is widely used in the production of carbon fiber and fiberglass composites. PTFE is used as a barrier between the carbon or fiberglass part being built, and breather and bagging materials The PTFE, used here as a film, prevents the non-production materials from sticking to the part being built, which is sticky due to the carbon-graphite or fiberglass plies being pre-impregnated with bismaleimide resin.
  • Clothes Irons. The sole plates of some clothes irons are coated with PTFE (Teflon™).
  • Computer Mice. PTFE is commonly used to coat the feet of gaming mice to reduce friction against the mouse pad.
  • Electrets (the electrostatic analogues of permanent magnets). The extremely high bulk resistance makes PTFE an ideal material for fabricating long-life electrets.
  • Food Processing. PTFE is widely used as a non-stick coating for food processing equipment. Examples include dough hoppers, mixing bowls, conveyor systems, rollers, and chutes.
  • Glaucoma Surgery. Expanded PTFE membranes have been used to assist trabeculectomy surgery to treat glaucoma.
  • Industrial Air Filters. PTFE-coated filters are often used to collect dust and particulate matter from air streams in applications involving high temperatures and high particulate loads. Examples include coal-fired power plants, cement production and steel foundries.
  • Industrial Applications. As a result of its low friction, PTFE is used for plain bearings, gears, side plates, seals, gaskets, bushings, and applications with sliding action. In these applications, PTFE outperforms acetal and nylon coatings.
  • Insect Containers. PTFE provides a smooth, non-stick surface than can be used as a lubricant to prevent captive insects from escaping.
  • Insulation of Wiring in Aerospace and Computer Applications. For example, hookup wire and coaxial cables. Because PTFE has excellent dielectric properties, especially at high radio frequencies, it makes an excellent insulator in connector assemblies and cables, and in circuit boards used at microwave frequencies. A high melting temperature, makes PTFE the material of choice as a high-performance substitute for the weaker and lower-melting polyethylene used in low-cost applications.
  • Laboratory Containers. High corrosion resistance makes PTFE an excellent liner for containers and coating for magnetic stirrers that contain highly corrosive chemicals, including hydrofluoric acid, fluoroantimonic acid, and superacid.
  • Laser printers. PTFE is often used in many parts of a laser printer, including heater elements, to prevent any kind of sticking.
  • Non-stick Cookware. PTFE is best known for its use a coating for non-stick frying pans and other cookware. PFTE coatings are hydrophobic (resist water) and have a fairly high resistance to heat.
  • Outdoor Apparel. PTFE can be stretched to contain small pores and then placed between fabric layers to make a waterproof, breathable fabric for outdoor apparel. It can also be used to protect fabrics and resist stains.
  • Ski Bindings. PTFE is often used in ski bindings as a non-mechanical AFDs (anti-friction devices).
  • Sports and Medical Applications. PTFE can be applied to pressure-sensitive adhesive backings and used in footwear, insoles and medical devices to prevent friction-induced blisters, calluses and ulcerations
  • Twisty Puzzles. Powdered PTFE is used in a suspension with a low-viscosity, azeotropic mixture of siloxane ethers to form a lubricant in twisty puzzles.
  • Hose Assemblies, Expansion Joints, and Industrial Pipelines. Because of its extreme non-reactivity and high temperature rating, PTFE is often used as the liner in hose assemblies, expansion joints and industrial pipelines, especially those using acids, alkalis, or other chemicals. Its frictionless qualities allow improved flow of highly viscous liquids, and for uses in applications such as brake hoses.

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