Global Butylene Glycol Bg Market By Type (Purity 99.5% Type, Purity 99.6% Type, Purity 99.7% Type, Purity 99.8% Type, Purity 99.9% Type, Others), By Application (PBT (Polybutylene terephthalate) Resin Raw Material, Polyurethane Resin Raw Material, and Other Polyester Raw Materials), By Region, and Key Companies - Industry Segment Outlook, Market Assessment, Competition Scenario, Trends and Forecast 2020-2029