Polytetrafluoroethylene (PTFE) is a fluoropolymer obtained by polymerising tetrafluoroethylene (TFE).
This article highlights the standard industrial PTFE manufacturing process.
How to Produce PTFE
In this section, we will look at the two main PTFE manufacturing processes.
Regardless of the process, the first stage is always the synthesis of tetrafluoroethylene.
Synthesis of Tetrafluoroethylene
Tetrafluoroethylene (TFE) is the resultant product of a chemical reaction of reacting fluorspar, hydrofluoric acid, and chloroform.
The reaction occurs in a chemical reaction chamber set at temperatures ranging between 590 – 9000C. The reaction yields a gas.
Next, the gas is cooled and then distilled forming liquid Tetrafluoroethylene (TFE).
Once you have your liquid TFE, you can commence the production of polytetrafluoroethylene.
Polymerization of tetrafluoroethylene results in polytetrafluoroethylene.
Various industries use different polymerization methods to manufacture PTFE depending on their specific requirements.
Below, we discuss two commonly used polymerization methods:
I. Suspension Polymerization
Suspension polymerization occurs in a reaction chamber.
Liquid PTFE is mixed with pure water and a reactant (which initiates the reaction process).
The reaction results in the production of solid grains floating on the surface.
For the reaction chamber to be effective, note the below:
- The reaction chamber requires shaking during the reaction. Consequently, ensuring efficient polymerization and subsequent formation of solid grains.
- For the reaction chamber not to overheat, it should have an outside covering of jackets filled with coolants.
- Lastly, the reaction chamber should be able to cut off the flow of TFE once the threshold weight is attained in the chamber.
After full polymerization, the water is drained. The residue left is moist PTFE which appears as grated coconut.
Next, moist PTFE is dried and granulated in a mill forming fine powder PTFE.
A manufacturer might opt to conclude the manufacturing process at this stage.
Alternatively, subject to the manufacturers’ discretion, they can opt to create lumps of PTFE. This is done through a process referred to as agglomeration.
Agglomeration entails vigorously mixing the fine PTFE powder with a solvent such as acetone. Preferably, the mixing is done in a rotating drum.
From mixing the solvent with the PTFE powder, you will be able to get PTFE moist PTFE pellets which are then dried in an oven.
II. Dispersion Polymerization
Similar to suspension polymerization, dispersion polymerization also entails the use of pure water and a reactor chemical.
Dispersion polymerization differs from suspension polymerization in FOUR main ways:
- In dispersion polymerization, there is no need for vigorous shaking of the reaction chamber. However, the chamber needs to be slightly rocked.
- The reaction results in the formation of bead-sized PTFE solids.
- Dispersion polymerization does not require the complete draining of water in the final stage.
- Mostly the final product will be a milky PTFE solution. But, there is also an option of drying the PTFE making it solid.
How to Manufacture Different Grades of PTFE
There are various grades of polytetrafluoroethylene. However, the main grades of PTFE are three:
- Virgin PTFE – Which has no modifications or filling.
- Chemically Modified PTFE – Having a composition that has undergone chemical alteration.
- Filled PTFE – This is filled with various components such as pigments, glass, carbon, graphite, aluminum, boron, and cobalt. The filling can be either one or a combination of these components.
The various grades of PTFE are either manufactured through dispersion or suspension polymerization.
Depending on the grade, a filler material will be added (for filled PTFE) or not be added (for virgin PTFE).
For the chemically modified PTFE there will be also an alteration of the chemical properties of the PTFE during polymerization.
What are the Advantages of PTFE?
PTFE has several properties that make it preferred in various applications. Such properties include:
- High friction and wear resistance –This is due to its self-lubricating nature. Consequently, guarantees the durability of the PTFE articles.
- Self-cleaning – reducing the need for cleaning equipment manufactured by PTFE
- High versatility – enabling its usage in several industries and applications regardless of temperature disparities.
- Superb corrosion resistance – making it an ideal material for making products that are used in corrosive environments.
- Non-flammable and inert – hence it acts as an effective non-stick coating for most cookware such as pans.
What are the Limitations of Polytetrafluoroethylene?
PTFE is ideal for most but not all applications. This is because of the below disadvantages:
- Unweldable – Consequently, is limited to applications that do not require welding.
- PTFE is a high-cost polymer – Owing to the complexity of its production.
- Not resistant to extremely high temperatures – PTFE will start melting when subjected to temperatures exceeding 326 0
- Difficult to mass produce – Hence economies of scale is not effective in the production of PTFE.
- Not ideal for high-pressure conditions – Which can lead to its deformation.
Is Polytetrafluoroethylene Durable?
Yes, polytetrafluoroethylene is durable because of the below properties:
- High friction resistance
- High heat resistance
Why is PTFE Hard to Manufacture?
PTFE is termed as difficult to manufacture due to the complexity of the manufacturing process.
Notably, PTFE manufacturing occurs in a controlled environment using sophisticated equipment.
Where do you use Polytetrafluoroethylene?
The versatility of polytetrafluoroethylene makes it an ideal material for various applications including:
- Electrical Industry – Wire and circuit board insulation
- Chemical Industry – Coating storage containers.
- Appliances, tools, and houseware – Coating utensils, cooking pans, and cloth irons.
- Manufacture of valves, gaskets, balls, and O-rings
However, all these different applications require distinct grades of PTFE.
How does Teflon compare to PTFE?
Outrightly, teflon and PTFE are the same thing. Teflon is a popular brand name associated with PTFE
What are the various ways of manufacturing PTFE products?
- Cold Compression Moulding – Ideal for rods, sheets, and bushes
- Ram Extrusion – Best for long tubes and rods
- Isostatic Moulding – Suitable for the valve seat, bushes, and insulator bushes
- Paste Extrusion – Flexible tubing and ropes.
- Hot Coining -Valves, nozzles, impellers
- Peeling – PTFE sheets and films
- Calendaring – PTFE seal tapes and ropes.
- Machining – Gaskets, valve seats, and balls
- Sodium Itching – Insulator rings and gaskets
- Coating Process – Utensils, iron bases, printing machine rollers, and textile rollers.
Polytetrafluoroethylene is a key material that most industries use in manufacturing various products owing to its unique properties.
However, each application needs a specific grade of PTFE for durability and easy machining.
For all your PTFE products, contact us now.
PTFE Sheet – Source: HANSA
Understanding Fluorpolymers – Source: AZO Materials
PTFE Rod – Source: HANSA
Polytetrafluoroethylene – Source: Wikipedia
PTFE Tape – Source: IQS Directory