| 摘要 |
PURPOSE:To form a polyester film for a magnetic recording medium with sufficient light-shielding characteristics and excellent surface flatness by incorporating uniformly carbon black particles and an org. compd. having infrared absorbing capability. CONSTITUTION:This polyester film for a magnetic recording medium contains carbon black particles and an org. compd. having infrared absorbing capability and exhibits characteristics satisfying the following three condition (1)-(3). (1) T900 (15mu)<=10%, (2) 0.005mu<=Ra<=0.02mu and (3) muk(50)<=0.03. In formulas 1-3, T900 (15mu) means light transmission (%) at the wavelength of 900nm in terms of film thickness of 15mum; Ra means an average surface roughness (mum) of a film and muk(50) means an abrasion coefficient of the film against a metal pin after the film is brought into contact with the metal pin and repeated runs of 50 times are preformed. |
