What drives the cost structure of unsaturated polyester resin production in China?

What drives the cost structure of unsaturated polyester resin production in China?
Unsaturated polyester resin (UPR) cost dynamics hinge on feedstock prices, primarily styrene, maleic anhydride, phthalic anhydride, ethylene glycol, propylene glycol, and diethylene glycol. From 2015 to 2017, costs rose as downstream demand outpaced domestic supply, forcing reliance on imports. From 2018 onward, new domestic capacity for these raw materials pushed prices down, easing resin producers' margins. Styrene, historically a volatile 'magic product' prone to speculative spikes, has become more rational after exchange listing and increased supply. Producers often price UPR on a fixed per-ton profit basis, meaning raw material swings directly impact gross margins, as seen when styrene jumped from RMB 5,240/t in 2020 to RMB 7,829/t in 2021, compressing margins by 5.8 percentage points for integrated players.