| 摘要 |
PURPOSE:To prevent picture defects or the like for reproducing even if a recording medium is placed in the atmosphere of a high humidity, by allowing the recording medium, which is formed with a resin containing a conductive sub- stance, not to include practically the inorganic salt of an alkali metal or the like. CONSTITUTION:A recordong medium formed with a resin containing a conductive substance does not include practically the inorganic salt of an alkali metal and an alkaline earth metal. For example, carbon black and ion exchange water are charged into a tank 1 and are agitated sufficiently, and moisture is eliminat- ed in a certain degree by a cake press machine and vacuum drier 2, and this material is dried up to about <=2% moisture contents by a driver 3 to obtain carbon black which does not include the alkali metallic salt or the like. A prescribed quantity of this cargon black is charged into a high-speed atitater 5 through a measuring equipment 4 and is mixed sufficiently with recording medium materials such as vinyl chloride resin, and an electrostatic capacity type video disc is produced through a prescribed process. |
