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Optical Brighteners -- Additives for Plastics


Optical brighteners are used to mask the inherent yellowness of plastics and are used to improve colors and make plastic look whiter and brighter. These are generally added to enhance the esthetics and consumer appeal. Optical brighteners are often used in conjunction with other colorants to achieve the specific shade as required by the application. Optical 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.

Optical brighteners are also known as fluorescent whitening agents. When exposed to UV light or black light these additives absorb the light in UV spectrum and reemits it in visible blue spectrum. This brighteners behavior could benefit from tracer additive. Tracers are very helpful in quality control specially to monitor uniformity and flaws in laminates and to examine uniform dispersion of additives in polymer matrix.