BIAXIAL ORIENTIERTER MEHRSCHICHTIGER POLYESTERFILM

摘要

A biaxially oriented laminated polyester film which is excellent in film winding properties and handling properties and provides excellent electromagnetic conversion characteristics when it is used as a base film for high-density magnetic recording media, particularly digital recording magnetic recording media. This film consists of a polyester A layer and a polyester B layer formed on one side of the polyester A layer and is characterized in that: (1) the polyester A layer contains three different types of fine particles which differ from one another in average particle diameter and has a surface roughness WRa of 5 to 20 nm and a WRz of 100 to 300 nm, (2) the polyester B layer has a surface roughness WRa of 2 to 10 nm and a WRz of 30 to 150 nm, and (3) the film has a friction coefficient of 0.5 or less.