Diafoil Company, Ltd.

Diafoil Hoechst Company, Limited

Diafoil Hoescht Company, Limited

Daifoil Company, Limited

Daifoil Hoechst Company Limited

Tomoyuki Kotani

Shigeo Utsumi

Narihiro Masuda

Kichinojo Tomitaka

Kazuo Endo

Yoshinori Sato

Satoshi Otonari

Takashi Harada

Seiji Sakamoto

Yujiro Fukuda

Chikakazu Kawaguchi

Masashi Inagaki

Masumi Koizumi

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

A biaxially oriented laminated polyester film for magnetic recording media, which has excellent surface uniformity, slittability, running property and cost performance, and in which a magnetic tape produced therefrom shows a very small number of scratches and a very small amount of abrasion dust.

Biaxially oriented laminated polyester film for magnetic recording media

A laminated polyester film for a magnetic recording medium having at least three layers, in which each of a top layer and a bottom layer of the at least three layers contains inorganic particles having a Moh's hardness of at least 8 and an average particle size of 0.005 to 0.5 .mu.m in an amount of 0.25 to 5% by weight based on the weight of the polyester of the respective layer and, in total, not larger than 0.20% by weight based on the whole weight of the polyesters of all the layers including an intermediate layer, and exposed surfaces of the top and bottom layers have coefficients of friction and surface roughness which satisfy the specific conditions.

Laminated polyester film for magnetic recording medium

A laminated polyester film for a magnetic recording medium which has a first polyester layer (A) containing inorganic particles (a) having a Moh's hardness of at least 8 and a specific average particle size and inactive particles (b) having a Moh's hardness of less than 8 and a specific average particle size larger than that of the particle (a) and a second polyester layer (B) containing inactive particles (c) having a Moh's hardness of less than 8 and a specific average particle size, wherein a content of the particles (a) is from 0.25 to 5% by weight based on the weight of the polyester in the layer (A) and less than 0.15% by weight of the whole weight of the polyester in the layers (A) and (B), the contents of the particles (b) and (c) are each 0.05 to 2.0% by weight of the polyester in the layers (A) and (B), respectively, and exposed surfaces of the layers (A) and (B) have coefficients of friction and surface roughness (Ra) which satisfy the specific conditions.

Laminated polyester film for magnetic recording medium comprising

A biaxially oriented polyester film simultaneously satisfying the following formulas (I) to (III):

Low-shrinkage polyester film and preparation thereof

Disclosed herein is a moldable biaxially stretched polyester film having a tensile strength at 100% elongation (F.sub.100), measured in an atmosphere of 150.degree. C., of 0.5 to 7 kg/mm.sup.2. The biaxially stretched polyester film according to the present invention is excellent in moldability.

Moldable biaxially stretched polyester film

A polyester film suitable for a base of high density magnetic recording medium containing barium ferrite as a magnetic material characterized in that the centerline average roughness (Ra) is not more than 0.025 .mu.m and the F.sub.5 value in the longitudinal direction is not less than 14 kg/mm.sup.2 is disclosed wherein the polyester film exhibit excellent better durability when used with barium ferrite as a magnetic material.

Polyester film for high density magnetic recording medium

A biaxially stretched polyester film which satisfies the following equations (1) to (4):

Process of making a biaxially stretched polyester film and biaxially

Minute-cellular polyester film

A film is disclosed, which comprises an at least uniaxially stretched finely cellulated polyester film of a high surface roughness having an apparent specific gravity in the range of 0.4 to 1.3 and an opacifying power of not less than 0.2, and a coating applied to either or both of the opposite surfaces of the polyester film. The coating applied to the minute-cellular polyester film serves the purpose of improving the adhesive property of the polyester film.

Growing community of inventors

Machida, Japan

Tomoyuki Kotani