Optical brighteners are used to mask the inherent yellowness of plastics and are used to improve colors and make plastic look whiter and brighter. Optical brighteners are often used in conjunction with other colorants to achieve the specific shade as required by the application. Brighteners have high melting point and show good dissolution in molten plastics. Bis-benzoxazolyl-stilbene and bis-benzoxazolyl-thiophene are the two common optical brighteners used in plastics industry.
