| 摘要 |
PURPOSE:To obtain an oriented film having fine surface roughness, substantial projection density and excellent wear resistance and running property by incorporating the BaSO4 particles in a specific average grain size range into polyester in a way as to maintain the product of the average grain size and weight % within a specific numerical range. CONSTITUTION:BaSO4 particles having 0.015-1.0mu average grain size are incorporated into a polyester film having the main repetitive unit consisting of polythylene terephthalate, at 0.05-2.0wt% by the weight of the polyester in such a way that the N satisfies 50<=N<=10,000 in the relation expressed by the formula when the average grain size of the BaSO4 particles is designated as Dmum and W is designated as the weight (weight %) of the particles to be added. Such polyester film is biaxially oriented to form a base for a magnetic tape and a magnetic layer is provided on the surface of the base. The tape which has fine surface roughness, has excellent slipperiness and is suitable for a video, computer, etc. is thus obtd. |
