| 摘要 |
PURPOSE:To provide the titled film for a magnetic recording medium, which has a degree of film roughness within a specified range and excellent lubricity, wear resistance, evenness, etc., by blending polyethylene terephthalate with a small amount of a 34C or higher fatty acid (derivative) and molding the mixture into a film. CONSTITUTION:100pts.wt. polyester composed of an acid component mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol is blended with 0.005-1pt.wt. 34C or higher fatty acid (derivative) (e.g., compds. of formulas II and III; 35<=n<=50). The blend is molded into a film, thus obtaining the desired polyester film for a magnetic recording medium, which satisfies the conditions represented by the formula III (wherein Ra is the average roughness on the center line of the film surface). The average roughness Ra on the center line of the film surface is a value determined according to JISB0601-1976.
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