| 摘要 |
PURPOSE:To obtain high electromagnetic conversion characteristics and high burst strength at the time of the formation of a magnetic tape by constituting at least one layer other than the outermost layer based on polyethylene -2,6- naphthalate of polyester of a polyethylene terephthalate component and setting the thickness of this layer to a specific ratio with respect to the whole thickness. CONSTITUTION:A biaxially oriented laminated polyester film is characterized by that at least the outermost layer is composed of polyester based on polyethylene -2,6-naphthalate and at least one layer other than the outermost layer is composed of polyester containing 20wt.% or more of a polyethylene terephthalate component. The thickness of the layer containing 20wt.% or more of the polyethylene terephthalate component is set to 1/50-1/2 the whole thickness of the film. These polyesters are dried to be laminated using two or more extruders, three or more manifolds and a confluent block to form a non- stretched film which is, in turn, biaxially stretched. When a non-sticking roll composed of Teflon or silicone is used, the smoothness of the film is improved. |
