0001519061 2026-09-30 2026-09-30 0001519061 false 00-0000000 8-K 2026-09-30 Trinseo PLC L2 001-36473 440 East Swedesford Road Suite 301 Wayne PA 19087 610 240-3200 false false false false Ordinary Shares, par value $0.01 per share TSEOF false