OPTICAL INFORMATION RECORDING MEDIUM

摘要

PURPOSE:To suppress the occurrence of spot defects at the interface between the substrate and reflecting film of a recording medium and to improve durability by using an acrylic copolymer having a specified intrinsic viscosity as the material of the substrate. CONSTITUTION:An acrylic copolymer having 0.3-1.0dl/g intrinsic viscosity obtd. by suspension polymn. using an azo polymn. initiator such as azobisisobutyronitrile is used as the material of the substrate of an optical information recording medium to form a substrate. A reflecting film made of a thin Al or Al alloy film is formed on the substrate by vacuum deposition and a protective film is further formed on the reflecting film to obtain the objective high quality optical information recording medium less liable to a change with the lapse of time and excellent in durability.