Thermal and fluorescent properties of optical brighteners and their whitening effect for pelletization of cycloolefin copolymers

The thermal and fluorescent properties of 4,4-bis(5-methyl-2-beazoxoazol)ethylene (Hostalux KS-N), 1,4-bis(benzoxazolyl-2-yl)naphthalene (Hostalux KCB), 2,5-bis-(5-tertbutylbenzoxazole-2-yl) thiophene (Uvitex OB), 2,2'-(4,4'-diphenolvinyl)dibenzoxazol (Uvitex OB-1), and 1,1'-biphenyl-4,4'-bis(2-(methoxyphenyl)ethenyl) (Uvitex 127) have been investigated. All of them exhibit good thermal stability ( > 300 degrees C) and high fluorescent quantum yields ( > 0.8). Furthermore, we also have successfully blended these optical brighteners into cycloolefin copolymers with the antioxidant (Irganox HP2921) to improve the discoloration after pelletization based on their whitening effect. (c) 2005 Elsevier B.V. All rights reserved.