Biaxially oriented polyester films

摘要

A biaxially oriented polyester film composed of a polyester composition comprising (A) 100 parts by weight of a substantially linear polyalkylene terephthalate having ethylene terephthalate as a main structural component, (B) 0.01 to 5 parts by weight of an ester of an aliphatic polyol having at least 4 hydroxyl groups in the molecule with an aliphatic monocarboxylic acid having at least 8 carbon atoms, and (C) not more than 0.8 part by weight of fine inorganic particles having an average particle diameter of not more than about 1 micron and being substantially insoluble in the polyalkylene terephthalate. The aforesaid biaxially oriented polyester film is useful as a base of magnetic tapes.