Plastic substrate with high performance by utilizing a new polycarbonate with addition of antiplasticizer
Masaya Ueda · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
This paper focused on the characteristics of DVD substrates using a polycarbonate with addition of a small amount of antiplasticizer. The addition of a meta-terphenyl, being categorized as an antiplasticizer, to a conventional Bisphenol A type polycarbonate resulted in a reduction of glass transition temperature (Tg) and an increase of flexural modulus of the composites simultaneously. These two counter wise effects of the composite generated better transcribability of grooves, lower in-plane birefringence, and better flatness of the injection modeled substrates without a sacrifice of transparency. In addition, the substrates exhibited lower water absorption. The meta- terphenyl acted as a general plasticizer at an elevated temperature over Tg and it filled the free volume between polymer chains below the Tg. The acting as a plasticizer and the filling of the free volumes generated better transcribability of grooves, lower in-plane birefringence at the metal state and higher modulus and lower water absorption at the solid state, respectively. These composites may have a great potential to widen a molding window of DVD without a drastic increase of a cost.