| 摘要 |
PURPOSE:To obtain an optical article having the excellent visibility of an image- formation by cooling a mold supplied with polyvinyl alcohol solution by placing it into contact with the liquid being at the ordinary temperature or less CONSTITUTION:PVA used herein may be of 95mol% or more in its saponifying degree, preferably, of 97mol% or more, and particularly, of 99mol% or more, besides it may be of 1,000 or more at the viscous average in its average copolymerizing degree, particularly, it may preferably be of 1,700 or more. It is preferable to use dimethylsulfoxide as an organic solvent for dissolving the PVA. The density of the PVA solution should be of such a range of 2-30 weight % in accordance with the directing strength of moisture containing rate. After the completely solved PVA solution is poured into the mold corresponding to the configuration of an optical article, it is cooled by placing it into contact with the liquid being ordinary temperature or less. The temperature of the liquid is preferably 0 deg.C or lower where the solvent of the PVA solution never freezes, more preferably, -10 deg.C or lower, moreover, it may preferably be -20 deg.C or lower. The liquid should be stirred desirably. |
