Diafoil Company, Ltd.

Diafoil Hoechst Company, Limited

Tdk Corporation

Mitsubishi Polyester Film Gmbh

Chikakazu Kawaguchi

Takashi Harada

Kazuo Endo

Yoshio Meguro

Seiji Sakamoto

Masashi Inagaki

Toshifumi Takisawa

Narihiro Masuda

Masahiko Fujimoto

Nobuyasu Shudo

Shigeo Utsumi

Tomoyuki Kotani

Kichinojo Tomitaka

Kenji Kato

Takashi Kagiyama

Kazuyuki Akatsu

Shigeyuki Watanabe

Kazuhiro Kunugihara

Yosio Meguro

Takahashi Harada

The present invention relates to a magnetic recording medium comprising: as a support film a biaxially oriented polyester film comprising

High-density magnetic recording medium

A biaxially oriented polyester film for a magnetic recording medium contains: 1) at least two different sizes of synthetic calcium carbonate particles; and 2) aluminum oxide particles to produce a film with excellent surface uniformity, running properties, and slittability wherein the film generates few scratches and low amounts of abrasion dust. The synthetic calcium carbonate particles are surface treated with a polycarboxylic acid, followed by treatment with a phosphorus compound. The biaxially oriented polyester film can comprise a layer in a multilayer film.

Biaxially oriented polyester film for magnetic recording medium

The disclosure describes a high-density magnetic recording medium comprising a biaxially oriented, laminated polyester film which is coextruded, so that a polyester A layer subject to plastic deformation by calendering treatment forms one of the surfaces of a base film, and

Magnetic recording medium having a calendered polyester layer with a

A novel biaxially stretched polyester film having excellent transparency and slipperiness is disclosed. The biaxially stretched polyester comprises a polyester composition which exhibits a film haze of not more than 1% after it is made into a film having a thickness of 100 .mu.m and 50-500 ppm on the basis of the weight of monodispersed cross-linked high polymer particles having an average particle diameter of 0.8-1.4 .mu.m and exhibits a deformability of 1.2-5.0 in a biaxially stretched polyester film.

Biaxially stretched polyester film

Disclosed herein is a polyethylene terephthalate film for magnetic recording medium, which contains 0.1 to 1.0% by weight based on the film of aggregated silicon oxide particles having an average particle size of 0.03 to 0.2 .mu.m, primary particle of which having an average particle size of 0.005 to 0.05 .mu.m, 0.1 to 1.0% by weight based on the film of aggregated aluminium oxide particles having an average particle size of 0.03 to 0.2 .mu.m, primary particle of which having an average particle size of 0.005 to 0.05 .mu.m and 0.005 to 0.3% by weight based on the film of a crosslinked polymer having an average particle size of 0.2 to 0.8 .mu.m, said film having a center line average surface roughness of 0.003 to 0.015 .mu.m and a sum of F-5 values in both the machine direction and the transverse direction of at least 25.0 kg/mm.sup.2. The film has a flat surface and is excellent in slipperiness, abrasion resistance, scratch resistance and protuberance resistance, which can be used as a base film for high-density magnetic recording medium.

Polyethylene terephthalate film for magnetic recording medium containing

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 in this invention is a polyester film for magnetic recording media, containing 0.05 to 5% by weight of inactive inorganic particles (A) having a Mohs hardness of 6 or above and an average particle size of 0.005 to 1.0 .mu.m and 0.01 to 2.0% by weight of inactive particles (B) having an average particle size which is greater than that of the particles (A) and in the range of 0.1 to 3.0 .mu.m, the polyester film having an intrinsic viscosity in the range of 0.52 to 0.65. The polyester film of this invention is excellent in abrasion resistance, scuff resistance and slitting qualities and useful as a base film for magnetic recording media.

Polyester film for magnetic recording media

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.

Disclosed herein is a polyester composition comprising 0.001-5% by weight of particles which have an average particle size of 0.05-5 micrometers, are mainly composed of calcium carbonate and contain 0.001-5% by weight of at least one compound selected from the group consisting of magnesium compounds, strontium compounds and barium compounds. Also disclosed herein is a process for preparing a polyester film by the electrostatic cooling method, which process is characterized by using the polyester composition of the present invention.

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Atsugi, Japan

Chikakazu Kawaguchi