Teijin Limited

Toshikazu Uchida

Toshifumi Osawa

Mitsuo Tojo

Masahiko Kosuge

Tomokatsu Ura

Akira Kameoka

Biaxially oriented laminate polyester film for magnetic recording medium

A biaxially oriented polyester film which has a difference between refractive index on the front side and refractive index on the rear side of the film of 0 to 0.002, a heat shrinkage factor of 0 to 0.6% when it is heated at 105&deg; C. for 30 minutes under no load, a Young's modulus of 4,609 MPa (470 kg/mm ) or more and a difference between the maximum value and the minimum value of Young's modulus on the film plane of 981 MPa (100 kg/mm ) or less, a center line average roughness on the film plane of 2 to 10 nm, and a static friction coefficient of 0.55 or less. A flexible disk having excellent electromagnetic conversion characteristics can be produced by forming an adhesive layer on both sides of the film and a magnetic layer on the adhesive layer.

Biaxially oriented polyester film and flexible disk

A composite polyester film comprising (1) a base film C of an aromatic polyester which does not contain or contains inert particles having an average particle diameter of 5 to 2,000 nm in an amount of 0.001 to 5.0 wt % based on the aromatic polyester; (2) a coating layer A on one side of the base film C, which comprises a binder resin, inert particles, a surfactant and a siloxane copolymeried acrylic resin, the outer surface of the coating layer A being not a surface for forming a magnetic layer thereon, and the siloxane copolymerized acrylic resin being contained in an amount of 1 to 50 wt % based on the coating layer A; and, (3) a coating layer B on the other side where the coating layer A is not existent of the base file C, which comprises one member selected from the group consisting of a siloxane copolymerized polyester resin, siloxane copolymerized acrylic resin, silicone and wax, a binder resin, inert particles and a surfactant, the outer surface of the coating layer B being a surface for forming a magnetic layer thereon, and the above member being contained in an amount of 5 to 90 wt % based on the coating layer B when the member is a siloxane copolymerized polyester resin or 1 to 50 wt % based on the coating layer B when the member is other than the siloxane copolymerized polyester resin.

Composite polyester film and magnetic recording medium

The present invention relates to a low electrostatic composite polyester film comprising a base film C, a coating layer A formed on one side of the base film C, and a coating layer B formed on the other side of the base film C, where (1) the coating layer A is formed of a water-soluble or water-dispersible resin coating inert particles and has a center line average roughness (Ra&minus;A) of the surface of 0.1 to 2 nm; (2) the coating layer B includes 1 to 40 wt % of inert particles and a composition containing a water-soluble or water-dispersible resin, the resin-containing composition containing 5 to 85 wt % of a silicone-modified polyester resin or 1 to 30 wt % of silicone or wax based on the layer B; and (3) the base film C is formed of an aromatic polyester. According to the present invention, it is possible to provide a composite polyester film useful as a base film for a magnetic recording medium that has low electrostatic properties and is excellent in not only blocking resistance and abrasion resistance but also electromagnetic conversion characteristics and adhesion to a back coat.

Lowly electrifiable composite polyester film

A film roll in which the distance from the center line of the film roll to the edge of the film extending in a film winding direction is slightly changed in a film breadthwise direction.

Growing community of inventors

Sagamihara, Japan

Toshikazu Uchida