Diafoil Company, Ltd.

Nobuyasu Shudo

Kazuo Endo

Chikakazu Kawaguchi

Masashi Inagaki

Toshifumi Takisawa

Yoshio Meguro

Masahiko Fujimoto

Shigeo Utsumi

Seiji Sakamoto

Kichinojo Tomitaka

Kenji Kato

Kazuyuki Akatsu

Shigeyuki Watanabe

Disclosed herein is a polyester film containing specific fine spherical silica particles. The film of the present invention is especially suitable as a base film for a magnetic recording medium or dielectric for a capacitor. The films of the present invention have the markedly improved properties such as surface properties, electromagnetic properties, electrical properties, etc. due to the excellent dispersibility of the particles in the film.

Polyester films, magnetic recording media and film capacitors produced

Disclosed herein is a polyester composition which comprises a polyester with a terminal carboxyl group content of 40 to 80 equivalents/10.sup.6 and 0.0 to 5 wt %, based on the total amount of the polyester composition, aluminum oxide particles of 0.005 to 5 .mu.m in average particle diameter and which has a melt resistivity of 6 x 10.sup.6 to 5 x 10.sup.8 .OMEGA..cm. By using the polyester composition, it is possible to successively produce a film having excellent wear resistance and flatness over a long production run.

Polyester composition

Disclosed herein is a polyester film containing specific fine spherical silica particles. The film of the present invention is especially suitable as a base film for a magnetic recording medium or dielectric for a capacitor. The films of the present invention have the markedly improved properties such as surface properties, electromagnetic properties, electrical properties, etc. due to the excellent dispersibliity of the particles in the film.

Growing community of inventors

Yokohama, Japan

Nobuyasu Shudo