| 摘要 |
PURPOSE:To improve the electromagnetic conversion characteristics and running characteristics in oriented polyester film employed as substrate of video tapes such as metallization type tapes, vacuum evaporation type tapes and the like by a method wherein specified particles of silica or titanium oxide and specified particles of calcium carbonate are employed in polyester. CONSTITUTION:Polyester, in which 0.01-0.5wt% of particles of either silica or titanium oxide with a mean particle size of 0.01-0.1mum and 0.005-0.3wt% of particles of calcium carbonate with a mean particle size of 0.01-0.1mum are contained, is orientated. Crystalline polyester such as polyethylene terephthalate, polyalkylene naphthalate or the like is employed as the polyester. Especially polyethylene terephthalate is preferable. The resultant film has excellent electromagnetic conversion characteristics for video tapes, the surface smoothness of which is requested, such as metallization type tapes, vacuum evaporation type tapes and the like and at the same time has favorable slipperiness, wear resistance and a durable running property. In addition, extremely few coarse particles, which cause to occur drop outs, are produced. |
