| 摘要 |
PROBLEM TO BE SOLVED: To simultaneously satisfy adhesive strength, abrasion resistance and scratch resistance. SOLUTION: A polyester resin is extruded in a molten state to form a sheet which is, in turn, stretched longitudinally and laterally to obtain a biaxially stretched film and this film is thermally fixed to a polyester base film for a magnetic recording medium. In this production method, the thermal fixing process is executed so that the first surface of the film is heat-treated at 170-190 deg.C for 1-50sec to bring the degree of surface crystallization of the first surface to 50-70% and the second surface of the film is heat-treated at 150-250 deg.C for 1-200sec to set the degree of surface crystallization of the second surface to 40-60% and the degree of the surface crystallization of the first surface is made higher than that of the second surface by 5% or more. |
