Optical brightener OB( OBA 184) CAS No. 7128-64-5 Appearance: Light yellow or milk white powder Purity: 99% min Melting point: 196-203â?? Usage: A good whitening agent for PVC,PS,PE,PP ABS, thermolastic plastics, Acetate fiber, paint, coating and printing ink, etc Package: 25KG fiber drums with PE liner