Hitachi, Ltd.

Waichi Nagashiro

Heigo Ishihara

Yoshiki Kato

Hajime Fukke

Munehisa Mitsuya

Katsuyoshi Chiba

Teruo Tsunoda

Motoo Akagi

Akira Osaki

Teruaki Kobayashi

Fuzio Maeda

Yoichi Oba

Atsushi Sumioka

Atsushi Kato

Mitsushi Endo

Tadao Okabe

Mitsuru Oikawa

A method of forming a lubricating film which comprises to apply an emulsion composed of a fluorinated polymer, a surfactant and a dispersing medium to a substrate and then dry the film, and a method of preparing a magnetic recording medium which comprises to apply the above method to a magnetic recording medium, are disclosed.

Method of forming lubricating film and a method of preparing magnetic

A magnetic recording medium comprising a substrate and, formed thereon, a magnetic layer comprised of magnetic particles bonded to each other with a thermosetting binder can be improved with respect to the durability by forming a number of fine pores in the magnetic layer and impregnating the fine pores with a lubricant. Particularly, when the fine pores have a diameter of 0.2 .mu.m or less and a rate of the fine pore in area of 3 to 30%, the durability can be improved while maintaining the noise during the recording and reproduction of information on a low level. In preparing the magnetic recording medium having such fine pores, it is preferred that an easily thermal-decomposable additive, such as polyalkylene oxide, be added to a magnetic layer forming paint. A magnetic recording medium having further improved characteristics can be produced by interposing an undercoating layer having a number of fine pores between the magnetic layer and the substrate, allowing the fine pores in the undercoating layer to communicate with the fine pores in the magnetic layer and impregnating the fine pores with a lubricant. In this case, in forming the fine pores, it is preferable to add an easily thermal-decomposable additive to a paint or extract a thermoplastic resin from a layer containing the thermoplastic resin with a solvent.

Magnetic recording medium and method for producing the same

A magnetic recording medium comprising a substrate and, formed thereon, a magnetic layer comprised of magnetic particles bonded to each other with a thermosetting binder can be improved with respect to the durability by forming a number of fine pores in the magnetic layer and impregnating the fine pores with a lubricant. Particularly, when the fine pores have a diameter of 0.2 .mu.m or less and a rate of the fine pore in area of 3 to 30%, the durability can be improved while maintaining the noise during the recording and reproduction of information on a low level. In preparing the magnetic recording medium having such fine pores, it is preferred that an easily thermal-decomposable additive, such as polyalkylene oxide, be added to a magnetic layer forming paint. A magnetic recording medium having further improved characteristics can be produced by interposing an undercoating layer having a number of fine pores between the magnetic layer and the substrate, allowing the fine pores in the undercoating layer to communicate with the fine pores with a lubricant. In this case, in forming the fine pores, it is preferable to add an easily thermal-decomposable additive to a paint or extract a thermoplastic resin from a layer containing the thermoplastic resin with a solvent.

A sufficient reproduced output can be attained even in a coating thickness of as small as 1 .mu.m, preferably 0.1 to 0.5 .mu.m with a magnetic recording medium comprising a substrate and a coating film containing magnetic powder formed on the substrate, wherein the content of the magnetic powder in the coating film is 66 to 90% by weight.

Magnetic recording medium

A composition of magnetic recording media consisting of a ferromagnetic powder such as .gamma.-Fe.sub.2 O.sub.3, a binder and single crystal alumina as a reinforcing agent. Single crystal .alpha.-alumina is preferably used as said single crystal alumina and its amount is preferably from 1 to 20% by weight based on the magnetic powder.

Composition of magnetic recording media

A method of manufacturing a paint composite for magnetic films wherein a mixture consisting of a magnetic powder, a polymer such as polyvinylbutyral, and a solvent is ground under a shear stress of 10-400 kg/cm.sup.2, and the ground mixture has a solvent, an epoxy resin and a phenol resin added thereto and is further ground. When a magnetic disk is produced using a paint which has been obtained by executing the first grinding under a shear stress of 10-400 kg/cm.sup.2 with a kneader or the like, it is endowed with excellent electric characteristics and surface flatness.

Method of manufacturing a paint composite for magnetic films

A process for the preparation of a magnetic recording medium comprising;

Process for the preparation of magnetic recording medium

A method for forming flat display panel phosphor dots is disclosed wherein a conventional printing method or procedure is used in combination with an optical method. The paste film containing the phosphor, photoresist and powdered glass is coated on the surface of the dielectric layer, e.g. lead glass layer by means of the printing method. The paste layer is irradiated by a ultraviolet light through a mask, and after the development of the paste layer has been completed, the remaining hardened portions of the paste layer are subjected to a heat treatment. In this way, phosphor dots having a desired shape can be formed very firmly and very exactly at certain predetermined portions on said dielectric layer.

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Kanagawa, Japan

Waichi Nagashiro