| 摘要 |
PURPOSE: To improve a productivity by setting a molding temperature to a softening temperature or lower of a cold rolled plastic sheet material, setting a pressure to be applied to a flowable pressure medium to a specific value, and shortening a time required for a molding step without necessity of preheating a sheet material before molding. CONSTITUTION: A polycarbonate sheet having a bisphenol A including, for example, a thickness of about 500μm, a molecular weight of 30,000, a softening temperature of 145 deg.C as a base is negative printed except two display regions with a considerably opaque black screen printing ink containing industrially used polyvinyl chloride/acrylic resin compound as a base. Thereafter, a colored sheet is punched so that the display regions are disposed at a predetermined interval from an outside profile. The thus prepared plastic sheet is disposed in a mold, heated to a softening temperature or lower of 80 to 130 deg.C, the colored surface is brought into contact with a pressure bell 7, the mold 1 is clamped, and the plastic sheet is molded by compressed air of 20 bar or more. And, a time required for the molding step of one cycle is 5 sec or less. |
