The SM plant is expected to remain down for 30 days.
Videolar-Innova, also a PS producer, was heard to be shutting down its SM plant in February because of programmed maintenance.
Unigel operates a 280,000 tonne/year SM plant at Cubatao, Brazil. Videolar-Innova operates a 260,000 tonne/year plant at Triunfo, Brazil, according to ICIS Plants and Projects.
SM is used to produce PS resins. It was not clear if the programmed shutdowns will hamper PS supply.
Unigel and Videolar-Innova are the major PS producers in Brazil.