Biaxially oriented laminate polyester film

摘要

A biaxially oriented polyester film has a first layer of an aromatic polyester containing inert fine particles having an average particle diameter of 1.0 mu m or less in an amount of 0.01 to 2% by weight and a second layer of an aromatic polyester. The ratio (t/d) of the thickness t of the first layer to the average particle diameter d of the inert fine particles is 5 to 30. The exposed surface of the first layer has a dynamic friction coefficient ( mu k1) against a metal of 0.15 to 0.50, the exposed surface of the second layer has a dynamic friction coefficient ( mu k2) against a metal of 0.24 to 0.60, and the ratio mu k2/ mu k1 is 1.2 to 4.0. The film has a thickness of 2 to 8 mu m.