To provide a biaxially oriented polyester film which has characteristics such as high strength, easy straight line tearability, impact resistance, heat resistance and dimensional stability, and is suitable for packaging materials, heat-resistant touch panels, electronic circuit substrates, cards, and capacitors, especially suitable as an easily tearable film useful as a packaging material.
This biaxially oriented polyester film having a sea-island structure comprising the sea component of a polyester (A) and the island component of an aromatic polycarbonate (B) is characterized in that the dispersion diameter of the island component is 0.01 to 5μm in at least one of the surface layer portions of the film in a depth range of from the surface to a depth of 1/5 and the aspect ratio of the island component in the central layer portion having a depth range of 1/5 to 4/5 in the depth direction from the surface of the film / the aspect ratio of the island component in the surface layer portion is 2 to 10.
TSUNEKAWA TETSUYA
MACHIDA TETSUYA
