Solvay will sell its business in cellulose acetate tow, a fiber used to make cigarette filters, to the private equity firm Blackstone in a deal worth $1.1 billion. The business, called Solvay Acetow, generated nearly $600 million in sales in 2015. It employs 1,300 workers and operates plants in Brazil, France, Germany, Russia, and the U.S. Separately, Solvay has agreed to sell its 59% stake in the Thai polyvinyl chloride producer Vinythai to Asahi Glass in a deal that values the firm at about $465 million. Solvay earlier sold its European PVC business and is selling its Brazilian PVC business.