| 摘要 |
PROBLEM TO BE SOLVED: To provide a biaxially oriented film excellent in moisture heat resistance and dielectric breakdown characteristics and to provide a biaxially oriented polyester film for obtaining a high-density magnetic recording medium having a less error rate, less chipping of a magnetic head or a magnetic tape, and excellent traveling durability. SOLUTION: The biaxially oriented polyester film includes a polyester (A) having a glass transition temperature of≥50°C to <130°C, an amorphous polyimide (B) having a glass transition temperature of >210°C to≤300°C, and an amorphous resin (C) having a glass transition temperature of≥130°C to≤210°C, wherein the total content of the polyester (A), the amorphous polyimide (B) and the amorphous resin (C) is≥80 mass% to≤100 mass% in the whole film weight; the content ratios by mass of the polyester (A), the amorphous polyimide (B) and the amorphous resin (C) are 70 to 99, 0.1 to 30, and 0.01 to 20, respectively; and the film shows a coefficient of expansion by moisture of 0 to 6.0 ppm/%RH in the film width direction. COPYRIGHT: (C)2010,JPO&INPIT |
