[no_toc] Testing of Whitening Agent
Appearance, volatile content, max melting point, content are typical testing items in Certification Of Analysis (COA) for each mass production batch.
How to test optical brighteners in plastics?
1.Immigration and bleeding
it is better to observe immigration and bleeding of optical brightener in UV lamp, yellow and green spots could be scattered on surface of plastics. The fluorescent light of spots is much higher than other areas.
The whitening effect of optical brightener agent could be estimated by visual method which better under the sunlight or measure by colorimeter.
There is no international standard for testing optical brightener lightfastness in plastics.most tests used DIN 54004 for reference. One may better and objective method is to test plastic whiteness movement with exposure time.