Silicones
Silicon-oxygen polymers sold as sealants, rubbers, fluids and resins for buildings, electronics, solar and cars; made from silicon metal, mostly in China.
Pseudo-commodities · Rubbers & elastomers · No. 60
- Single chemical
- Feedstock: Minerals and salts
- about 3-3.5 Mt of siloxane a year (2025, indicative, basis: silicon metal output of 4.6 Mt (USGS MCS 2026) with roughly a third going to silicones at about 0.44 t Si per t siloxane)
- 7.5 t CO₂e per t
- HS 391000
The sealant holding a glass tower's windows starts as silicon metal, and China makes about 70% of the world's siloxane.
Chart: Illustration: Silicones
Where it comes from
Chart: Map of where it comes from
Powdered silicon metal reacts with methyl chloride over a copper catalyst at about 280-300 C. The chlorosilanes are hydrolysed into siloxane and built into polymers.
Three things to know
- Silicones stay flexible from about -50 C to over 200 C, which makes them hard to replace in seals and electronics.
- Chinese siloxane traded at about CNY 10,700 a tonne in mid-June 2025, close to cash cost.
- Dow is closing its Barry plant in the UK by mid-2026, part of closures costing $630-790 million.
The journey
- 1 Silicon metalAbout 4.6 Mt made worldwide, 2025
- 2 Methyl chlorideFrom methanol and recycled HCl
- 3 Direct processSilicon plus methyl chloride over copper
- 4 Siloxane (DMC)Chlorosilanes hydrolysed with water
- 5 FormulationsFluids, rubbers, sealants, resins