How PTFE is made

PTFE was found by accident in 1938, when a cylinder of refrigerant gas turned into slippery white powder.

stations: 5
things upstream: 8
raw sources: 6
steps from the ground: 3

The short version

PTFE is made from tetrafluoroethylene gas, which a chemical plant produces from fluorspar, sulfuric acid and a chlorine-containing intermediate. The gas is polymerized in water under pressure into a slippery white powder or dispersion. It can be dried, ground, or compressed and heated into solid shapes, because it does not melt into a flowing liquid.

Make hydrofluoric acid

Fluorspar, the mineral calcium fluoride, is treated with sulfuric acid to give hydrofluoric acid. It is handled in specialist plants because it is dangerous.

Goes in
Sulfuric acid Fluorspar
Make the fluorocarbon gas

Hydrofluoric acid reacts with chloroform, which is made from natural gas and chlorine. Heating the product forms tetrafluoroethylene.

Goes in
Natural gas Chlorine
Polymerize it in water

The gas is pumped into a stirred reactor of water, where an initiator makes the molecules link into a chain of carbon wrapped in fluorine. The result is a powder or a milky dispersion.

Goes in
Water
Wash, dry and mill the resin

Solids are washed, dried and ground to the grain size the buyer wants. Fine powder goes into coatings and coarse powder is pressed into blocks.
Press and sinter the shapes

PTFE does not flow when it melts, so molders press the powder cold into a block and then bake it so the grains fuse. The block is machined into seals or skived into tape.

End of the linePTFE Next it goes into razor blade, nonstick pan, raincoat.

Worth repeating

Roy J. Plunkett found PTFE on 6 April 1938 when a cylinder of tetrafluoroethylene gas turned out to contain a white powder.
PTFE is a carbon chain surrounded entirely by fluorine, and it is heat resistant and chemically inert.
DuPont used PFOA for decades during PTFE production and later stopped after legal actions over health effects.