| 摘要 |
PURPOSE:To obtain a homogeneous optical disc substrate in a short period of time by a method wherein a forced heating such as microwave heating or the like is performed at the time, when a radical polymerization of an unsaturated compound reaches its ceiling temperature. CONSTITUTION:In a radical polymerization of an unsaturated compound, there exists a temperature, at which the reaction rates balance with each other and beyond which no polymerization proceeds. Said temperature is called the ceiling temperature of the compound. Concretely, at the ceiling temperature, the rate of polymerization reaction and the rate of depolymerization reaction where monomers leave successively from terminals of active chains become nearly equal to each other and the apparent reaction stops. When energy is given to the reaction system by heating at this time, the polymerization reaction proceeds again and the reaction completes in a short time, and only a slight amount of unreacted monomer is left, the hardness of the reaction product becomes high enough to be released from a mold. Accordingly, a homogeneous optical disc substrate is molded in a short time by accelerating curing of the substrate through microwave heating over the period of time excluding the time from a gel time to the time, at which the ceiling temperature is attained. |
