| 摘要 |
<p>PURPOSE: A biaxially oriented polyester film of three or more layers, its preparation method and a magnetic recording medium containing the film are provided, wherein the film is improved in an abrasion property, electromagnetic properties and a coiling property, and is useful as a magnetic film and a heat transfer ribbon. CONSTITUTION: The polyester film comprises an outer protective layer(A) and an outer protective layer(C); and a base layer(B) between the two protective layers, wherein the outer layer(A) has a roughness profile gas flow greater than 1,000 sec and less than 2,000 sec, and the outer layer(C) has a roughness profile gas flow of less than 600 sec. Preferably the outer layers(A, C) contain 500-10,000 ppm of particles. The middle particle size(d50) of the particles of the outer layer(A) is 0.1-0.6 micrometers; and the middle particle size(d50) of the particles of the outer layer(C) is 0.4-1.0 micrometers. The roughness profile gas flow of the outer layers(A, C) is controlled by changing the middle particle size(d50).</p> |
