Global Optical Whitening Agent Market By Type (Stilbene Type , Coumarin Type , Pyrazoline Type , O-phthalimide Type , and Benzene Nitrogen and Oxygen Type), By Application (Paper , Fabrics , Detergents & Soaps , Synthetics & Plastics , and Other), By Region, and Key Companies - Industry Segment Outlook, Market Assessment, Competition Scenario, Trends and Forecast 2019-2028