Unsaturated polyester resins
Low-cost thermosetting resins of maleic and phthalic polyesters dissolved in styrene, the matrix for glass-fibre pipes, tanks, boats, panels and engineered stone.
Pseudo-commodities · Resins & fibres · No. 65
- Single chemical
- Feedstock: Oil, gas or coal
- about 6.5-7 Mt a year (2024-2025, indicative, basis: China demand of 3.31 Mt in 2024 at roughly half of world volume); China output 3.45 Mt (2024e)
- 2.8 t CO₂e per t
- HS 390791
The kitchen quartz counter, the fibreglass boat and the water tank on your roof may all share one cheap resin.
Chart: Illustration: Unsaturated polyester resins
Where it comes from
Chart: Map of where it comes from
Glycols and maleic and phthalic anhydrides are cooked in batch reactors at about 190-210 C for 10-20 hours, then thinned in styrene to make the saleable resin.
Three things to know
- China made 3.23 Mt of UPR in 2023 and about 3.45 Mt in 2024, slightly above its own demand of about 3.31 Mt.
- UPR is about one-third styrene, so styrene prices, $1,030 a tonne in Asia on 2 March 2026, drive resin cost.
- Resin has a shelf life of only about 3-6 months, so most is sold close to where it is made.
The journey
- 1 FeedstocksAnhydrides, glycols and styrene
- 2 Polyesterification190-210 C for 10-20 hours
- 3 Styrene thinningDissolved in about 30-40% styrene
- 4 CompoundingGlass fibre, quartz and calcium carbonate
- 5 CuringPeroxide and cobalt set it hard