| 摘要 |
PURPOSE:To improve a quality, by constituting a jacket of a rigid polyvinyl chloride sheet to which irradiation ray bridge treatment has been executed, securing the thermal stability and dimension property of the jacket, and stabilizing its recording and reproducing characteristic. CONSTITUTION:An original sheet of about 200mu thick is obtained by use of materials consisting of composites shown in the table, and through a prescribed process, a jacket sheet material body 6 having prescribed size is punched, a cleaning sheet material body 7 is placed on it, and they are melt-stuck by heating. Also, the jacket sheet material body 6 is bent so that the cleaning sheet material body 7 becomes its inside, heating the center bent part of the jacket sheet material body 6 by a heater 12. In this way, in this hollow part, a jacket 2 and a cleaning sheet 3, in which a magnetic disk 1 has been stored are obtained. After that, for instance, an electron beam 13 whose acceleration voltage is 750kV is irradiated to the jacket 2 by 10 megarads, a bridge reaction is caused by a bridge agent, and rigid polyvinyl chloride to which radiant ray bridge treatment has been executed is obtained. |
