| 摘要 |
PURPOSE:To ensure both at least a predetermined level of coefficient of friction at the time of processing and a low coefficient of friction of a product, by specifying the coefficient of transfer of a lubricant from a magnetic layer upon contact of a film surface with a magnetic surface, in terms of the change in the coefficient of friction of the film surface caused by the transfer, and specifying the number of protrusions on the surface of a laminate film and the relative standard deviation of height distribution of the protrusions. CONSTITUTION:A biaxially oriented thermoplastic resin film for magnetic tape base comprises a film containing a thermoplastic resin A and inactive particles as main constituents and laminated by coextrusion with a film containing a thermoplastic resin B as a main constituent, on at least one side thereof. The laminate film surface side of the resin A is the side opposite to a magnetic layer, and the film surface has a coefficient of transfer of a lubricant from the magnetic layer upon contact thereof with the surface of the magnetic layer, in terms of the change in the coefficient of friction of the film surface caused by the transfer, of 0.07-0.3. The number of protrusions formed on the laminate film surface side of the resin A by the inactive particles is at least 10,000 per square millimeter, and the relative standard deviation of height distribution of the protrusions is not more than 0.6. |
