Study on Deterioration Mechanism and Acceleration Tests for Optical Transparent Materials

If transparent resins used in components (such as lens and sealant) of optical devices are exposed to light or heat or made contact with metal, their performance may be lowered (discolored), leading to lower optical device functions (such as transmittance and brightness). The authors have recently attempted to find out how they deteriorate, using various analysis methods, by focusing on discoloration that occurs on the boundary face of sealant silicone resin with silver. When silicone resin (methylphenyl silicone) is heated while it is kept touching silver, it discolors. The heat activates a slight amount of copper impurities in the silver, leading to the carbonization of broken-down phenyl radicals and the bonding of released phenyl radicals with additives. It is speculated that the discoloration occurs because the carbonization and bonding cause the conjugated system to shift toward long wavelengths.