| 摘要 |
PURPOSE:To suppress generation of swarf and dust, etc. at the time of slitting by forming a 3-layered laminate structure having a light shielding layer of the same width as the width of a magnetic tape or the slightly narrower width as its core layer continuously in the longitudinal direction of the film. CONSTITUTION:PE terephthalate A which is added with 0.25wt% kaolin having 0.6mum average grain size and has 0.6 intrinsic viscosity is melted in an extruder. PE terephthalate B which is added with 10wt% titanium oxide having 0.3mum average grain size and has 0.6 intrinsic viscosity is melted in another extruder. The melts thereof are introduced into a die, are extruded from the die and are quickly cooled by a cooling drum, by which an unstretched film having about 200mum thickness is obtd. The 3-layered laminate part of the film is so formed by said die that the terephthalate B is constructed as the core layer and the terephthalate A as both outside layers. The 3-layered laminate structure is so formed that the core layer has 2.5mm width and 55mum thickness and the thickness of the outside layers is about 73mum.
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