PTFE Technical Specification

PTFE Technical Specification

1.What is PTFE?

PTFE is the abbreviation of polytetrafluoroethylene. It is a synthetic fluoropolymer that combines carbon and fluorine. PTFE, and other fluoropolymers alike, such as FEP and PFA, shares similar fields of applications. The fluoropolymer is the main material to make tubing for medical, pharmaceutical, chemical, and other industrial equipment. Aside from tube making, PTFE is an ideal material for coating as well. Applying a PTFE layer onto metals, fabric, and other materials improves a given product’s quality. In this article, we will talk about the properties and applications as well as other aspects with respect to the use of PTFE.

Yes, PTFE is Teflon. There are tons of terminologies out there for plastics, polymers, and synthetic materials. It easily gets confusing for people to figure out exactly which is what and we get it. PTFE is the chemical term. It indicates what this material is. Teflon is the brand name owned by the company Chemours. Teflon was discovered in 1938 by DuPont’s chemist, Dr. Roy Plunkett, and later managed by Dupont’s spin-off company, Chemours. Chemours registered the trademark Teflon in 1945. Today, the company is still developing PTFE products with higher performance under the brand name Teflon.

PTFE is made by polymerizing TFE (tetrafluoroethylene) and the main ingredients are fluorspar, chloroform, and hydrofluoric acid. The process starts by synthesizing these three ingredients to produce TFE. This step is called pyrolysis. It is a chemical reaction process where these ingredients are heated to between 590-900 degrees Celsius in an autoclave to fuse together. TFE comes in the form of a colorless (transparent), odorless, and toxic-free gas. TFE is highly flammable and explosive so it is almost impractical to transport the material. Therefore, the polymerization of TFE is usually conducted on-site, right after the production of TFE. Making PTFE requires cooling and distilling to purify TFE prior to the polymerizing process.

The polymerization of high-purity TFE involves the use of the initiator (reaction agent) and pure water. PTFE manufacturers use different recipes and initiators in their own polymerization process. The agent can be bisulfites, di-tertbutyl peroxide, disuccinic acid peroxide, ammonium persulfate (APS), and azo-based initiators, to just name a few. In terms of the process, the two main methods are dispersion polymerization and suspension polymerization. The former method produces PTFE paste that can be further processed into fine powder. It is ideal for metal coating and fabric finishing. The latter makes PTFE pellets, which can be molded, sintered, etc. into various PTFE products.

4.What are the properties of Teflon?

Teflon is applicable in fields that demand products with durable and robust physical properties, for instance medical, automotive, electronics, military industries, etc. Here are the major characteristics of Teflon.

Note : PEEK is not a Fluropolymer, it is listed only for comparison purposes under high pressure and temperature operating environment.

4.1.Heat and chemical resistance

First of all, Teflon is heat-resistant. Or, to be exact, Teflon can withstand high temperatures compared with other plastic materials. It has a melting point of around 327 degrees Celsius so there are few circumstances heat damages Teflon. Secondly, Teflon is chemically inert. It does not react to most chemicals, which makes it preferable in the chemical, petrochemical, and pharmaceutical industry where the equipment handles corrosive chemicals on a daily basis.

4.2.Low friction coefficient

Another essential characteristic of Teflon is its low friction coefficient. This is what most people describe as the non-stick property. Chemically speaking, the molecules of Teflon are wrapped by fluorine. Fluorine on the surface layer prevents other materials from attaching to PTFE. That is why Teflon has the non-stick property. This trait is especially beneficial to the cookware. The non-stick pan is so convenient that we can find at least one piece of cookware with the Teflon coating in virtually every household today. That being said, Teflon coating is applied on other products to minimize friction or provide a better surface finish.

4.3 Wear/weathering resistance & electrical insulation

PTFE not only resists heat and chemicals. It has little to no friction, is resistant to wear and weather, and has good electrical insulation. PTFE can work and maintain high performance over time in harsh working environments due to its excellent wear and weathering resistance. It can hold out against pressure and forces, making it a good protection material for equipment in outdoor settings. The low electrical conductivity is ideal for semiconductor manufacturers. So, what are some common applications?

5.Applications

The application of Teflon is nearly limitless with all these benefits. Most people think of cookware when it comes to Teflon. However, there is more to PTFE’s application. In the following section, we are going to talk about some PTFE-involved products people are not aware of.

5.1.Lubricant

PTFE is used as dry lubrication in areas where low friction is required, with cookware coating being one of them. PTFE can reduce the friction effectively between surfaces and it gives an additional protection layer against corrosive substances as well. The WD-40 spray with PTFE is used for chain lubrication. It leaves a thin film on the chain so that it can resist dirt and oil.

5.2.Piping/tubing

As mentioned earlier, Teflon coating is on the surface of the piping/tubing system in facilities that handle highly corrosive fluid. The Teflon coating on the inner surface of valves, pumps, tees, fittings, and every joint in the piping system is crucial for it prevents the risk of fluid leakage. The leakage of corrosive fluid is hazardous to both the equipment and the staff members in the working area.

5.3.Fabric/textile

One of the benefits we haven’t mentioned yet is the hydrophobic property. Teflon is water repellent and can easily coat fibers. Outdoor clothing brands use the technology to design garments and shoe fabrics to make water-repellent products. The famous, and probably the most successful waterproof fabric, Gore-tex, derives from PTFE. Gore-tex is a patented fabric called ePTFE (expanded PTFE), which is renowned for its waterproof yet breathable characteristics.

5.4.Ammunition

A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. The best known fluoropolymer is polytetrafluoroethylene(PTFE).
Fluoropolymers have superior heat resistance, chemical resistance, good electrical insulation. Besides the above characteristics, fluoropolymers also carry nonstick and low-frictional properties. 

The best known fluoropolymer is polytetrafluoroethylene(PTFE), and it exhibits outstanding resistance to chemical, resists all chemicals except fluorine gas, chlorine trifuloride, and molten alkali metals. But when in high temperature, PCTFE is slightly susceptible to ammonia and chlorine gas.

Among fluoropolymers, PTFE exhibits the lowest frictional coefficient and provides unique self-lubricating properties.

It can be used up to 260 degree C.Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The commonly known brand name of PTFE-based compositions is Teflon™ by Chemours, a spin-off from DuPont, which originally discovered the compound.

5.5.Aerospace/aviation

PTFE provides excellent electrical insulation, which is applicable to aircraft and spacecraft. An airplane requires a large number of precision electronics to operate and there are millions of feet of cables and wiring units that connect these devices. As a result, insulation that has excellent dielectric properties to provide long-term protection to electrical parts is necessary.

6.Is PTFE safe or harmful?

PTFE is widely used in cookware and pharmaceutical industries. Though PTFE does not enter our body directly, but the food and drugs have close contact with it during processes. This raises a concern to people whether PTFE poses a threat to our health or not. Fortunately, Teflon alone does not harm our health when we consume it. However, there is a chance it damages our body. When it is heated over 300 degrees Celsius, where PTFE starts to break down, it emits polymer fumes.

Though the chance is scarce, if exposed to the fume over a long time, it is very likely to cause symptoms such as chest discomfort, headache, and fever. For this reason, it is recommended not to preheat the nonstick pan or use it over the power burner. When heated up to 260 degrees Celsius (500 degrees Fahrenheit), the coating starts to decompose and release fumes. Empty nonstick pans can reach this temperature within five minutes. If we use the nonstick pan only on low to medium heat, it is safe.

7.Final words

The use of PTFE and other types of fluoropolymers is advantageous in many application fields. Though it does come with several limitations and potential risks, the advantages still outweigh the disadvantages. It is totally possible to avoid those drawbacks if we use these materials correctly. Bueno Technology is an expert in fluoropolymers. We manufacture pumps, valves, and pipe/tube fittings using fluoropolymer coatings. Contact us right now if you need more information on our products.

Types of fluorine resins and their chemical resistance comparison:

 

Category (Name)	Molecule Structure (Fluorine per molecule)	Melting Point and Operating Temperature	Chemical Resistance
PTFE		m.p. 327oC W.TEMP(MAX) 260oC	Excellent chemical stability; PTFE don't interact with the vast majority of chemicals and solvents. However, it is vulnerable to molten alkali metal. PTFE also interacts with fluorine gas and fluorine compounds, such as CIF3. OF2, under high temperature and high pressure environments
ETFE		m.p. 270oC W.TEMP(MAX) 150oC	Similar to the chemical resistance of PTFE, but easily corroded by nitric acids. Has chemical resistance on par with PTFE, but easily corroded by certain chemicals such as nitric acid.
ECTFE		m.p. 240oC W.TEMP(MAX) 150oC	Highly crystalline, high polymer material, with superior permeability properties.
PFA		m.p. 302~310oC W.TEMP(MAX) 260oC	Similar to the chemical resistance of PTFE, with superior mechanical and sanitary properties.
FEP		m.p. 253~282oC W.TEMP(MAX) 160oC	Similar to the chemical resistance of PTFE, but has slightly lower operating temperature.
PVDF		m.p. 170oC W.TEMP(MAX) 130~150oC	Easily dissolved by fuming sulfuric acid, high temperature sulfuric acid, or caustic soda above 100oC; also bloats or dissolves when interacting with strong solvents such as aceton、ketone、DMA, acetamide or extremely alkalic primary amine such as n-butylamine.