| 摘要 |
PURPOSE:To improve running durability and chipping resistance in repeated use, by dispersing a specific magnetic powder in a polyester, molding the dispersion into film and biaxially orienting the film. CONSTITUTION:In a polyester with an intrinsic viscosity (in o-chlorophenol, 35 deg.C) of pref.0.4-0.9, prepd. from an acid component comprising mainly an arom. dicarboxylic acid and a glycol component comprising mainly an aliph. glycol (e.g., polyethylene terephthalate) is dispersed 0.01-1.0wt.%(based on said polyes ter) magnetic powder with a mean particle diameter of 0.05-2.0 and an aspect ratio (long diameter/short diameter) of 1.1-2.7, pref.1.1-2.0, selected from the group consisting of ferromagnetic iron oxide, ferromagnetic chromium dioxide and ferromagnetic alloy powder. The dispersion is fused and molded into film to give an amorphous nonoriented film, which is then biaxially oriented, heat set and, if necessary, annealed. |
