| 摘要 |
PURPOSE:To improve the reliability and manufacture yield of a disk type recording medium by using conductive carbon black purified by removing impurities. CONSTITUTION:200g carbon black which has 30mum grain size, 950m<2>/g surface area, 350ml/100g oil absorption, pH 9.0, and 0.5% ash content is dispersed in 2.5l pure water, stirred for one hour at the room temperature, and filtered by suction and then washed with 10l pure water. This is dried in air at 120 deg.C for 15hr, and consequently its ash content is reduced to 0.29%. Then, a mixture of composition of 20pts. dried black, 100pts. vinyl chloride-lauryl acrylate copolymer, 3pts. stabilizer and 2pts. lubricant is mixed thoroughly by a high-speed stirring machine and then kneaded by melting with hot rolls; and compression molding is carried out to obtain a disk body 1 which has a center hole 2. Bits 3 which correspond to an information signal are as shown in Fig. |
