POLYESTER FILM FOR MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To obtain a polyester film for a magnetic recording medium, having smoothness and scratch resistance without detriment to electromagnetic transduction characteristics and showing good running performances even under conditions of high temperatures and high humidity using a polyester film containing a specified amount of colloidal silica having a specified particle diameter. SOLUTION: This polyester film for a magnetic recording medium contains at least 0.005wt.% colloidal silica having a content of particles of a particle diameter of 2a (μm) or below of 95wt.% (wherein (a) (μm) is the mean particle diameter). The polyester of which the polyester film is made mainly consists of a linear polyester such as polethylene terephthalate or polytetramethylene terephthalate.