MAGNETIC RECORDING MEDIUM AND ITS PRODUCTION

摘要

PURPOSE:To make a relative speed between a head and a disk approximately constant and to increase the recording range by using a cylindrical thermoplastic film as a substrate and coating the substrate with a magnetic metallic thin film either on the surface side or the back side. CONSTITUTION:A magnetic metallic thin film 2 is formed on the surface and/or back side of a substrate made of a cylindrical thermoplastic resin film having a smooth and seamless surface. A compound which is hardened by heat is coated on the film 2. Such substrate 1 is heated up at a <=100 deg.C temperature to form a protecting film 3. In such processes, a magnetic recording medum 5 is otained. The substrate 1 is produced in the following process. That is, a polyester sheet having a smooth surface is cut into a prescribed size. Thus cut sheet is set into a vacuum molding device to undergo a preheating process and sucked under vacuum onto a cylindrical male mold having a mirror surface which is kept at a prescribed temperature to be held there for a certain period of time. Then the molded product is released from the mold.