OPTICAL INFORMATION RECORDING CARRIER

摘要

PURPOSE:To obtain an optical disk which has a high signal recording characteristic and is suitable for long-period preservation of information by decreasing the acrylate monomer to be included into a replica. CONSTITUTION:A transparent thermoplastic substrate to be used as a recording film carrier is polymethyl methacrylate (PMMA) consisting of a copolymer of methyl methacrylate and methyl acrylate by a continuous mass polymn. method. Recombination reaction and the disproportionation reaction by which terminal double bonds are generated arise as the termination reaction at the time of polymer polymn. The terminal double bonds are the start point of the polymer thermal decomposition and a decrease of a monomer decomposition rate is permitted by decreasing the polymn. termination ratio by the disproportionation reaction. More specifically, the disproportionation reaction is decreased to decrease the terminal double bonds and the methyl acrylate is copolymerized with the methyl methacrylate by the continuous mass polymn. method as the PMMA resin to be used for an optical disk, by which the replica withstanding wide molding conditions and having the high long-period reliability is obtd.