Hitachi, Ltd.

Hitachi Maxell, Limited

Heigo Ishihara

Takanori Kudo

Hajime Fukke

Waichi Nagashiro

Katsuyoshi Chiba

Hiroyuki Matsumoto

Yutaka Ito

Yoshiki Kato

Takayuki Nakakawaji

Hiroshi Tani

Akira Osaki

Munehisa Mitsuya

Teruo Tsunoda

Naoki Kodama

Tomoyuki Ohno

Yasutaro Uesaka

Motoo Akagi

Iwao Matsuyama

Mina Ishida

Teruaki Kobayashi

Masayuki Katsumoto

Fuzio Maeda

Hiroshi Sasaki

Masaaki Futamoto

Akira Kato

Yukio Honda

Kazuetsu Yoshida

Tomoyuki Hamada

Shuji Imazeki

Yoshinori Honda

Tetsuya Hamaguchi

Kenji Furusawa

Tsuneo Suganuma

Takashi Nishimura

Yoichi Oba

Mitsuyoshi Shouji

Yuichi Kokaku

Hisashi Morooka

Mitsushi Endo

Hitoshi Inoue

Yoshiharu Terada

Yuko Morita

Hiroaki Hagimae

Mitsuyoshi Ootake

Selichi Asada

A lubricant which does not splash easily and has an improved property of slidableness, and a magnetic disk using the lubricant are provided. A magnetic disk apparatus featuring a prolonged service life of a stable operation and an excellent record reproduction property is provided by installing the above magnetic disk. The lubricant of the invention contains perfluoropolyether expressed by the following general formula, in which a component of its molecular weights less than 1000 is smaller than 10 wt. %, a component of its molecular weights not less than 7000 is smaller than 15 wt. %, a ratio between a weight average molecular weight and a numeric average molecular weight is 1.5 or less, and a substitution ratio of its terminal functional group is not less than 90%:R&#x2014;CFO&#x2014;[&#x2014;(CFCFO)&#x2014;&#x2014;(CFO)&#x2014;&#x2014;]&#x2014;CF&#x2014;R&#x2003;&#x2003;(1),where R1 and R2 are univalent organic groups, m and n are positive integers. Further for the magnetic disk which rotates at a speed of 10000 rpm or more, a lubricant containing a perfluoropolyether expressed by the following general formula is used, in which its numeric average molecular weight is not less than 5500, a component of molecular weights less than 3000 is 15 wt. % or less, a ratio between its weight average molecular weight and its numeric average molecular weight is 1.5 or less, and a substitution ratio of its terminal functional group is not less than 90%:HOCH&#x2014;CFO&#x2014;[&#x2014;CFCFO]&#x2014;&#x2014;[CFO]&#x2014;&#x2014;CF&#x2014;CHOH&#x2003;&#x2003;(2),where m and n are positive integers.

Lubricant, magnetic disk and magnetic disk apparatus

A thin film magnetic disc in which dot-like scattered bumps, made of a material different from that of the protective layer, are formed on the protective layer, and a lubricant layer is formed on the surfaces of the protective layer and the scattered bumps. A protective layer excellent in strength and disk durability is obtained by using a material different from that of the bumps. The functions of the protective layer and scattered bumps are separated from each other and make full use of the different materials. Such a protective layer is effective to reduce spacing between a head and the disc.

Thin film magnetic disc and method of manufacturing the disc

The present invention is aimed at providing a magnetic disk and a magnetic disk apparatus both of which have a high performance lubricating film which makes continuous sliding endurance and low adhesiveness compatible, and a lubricating film having a self repairing function which makes it possible to recombine scratched off lubricating agent from the magnetic disk surface by sliding with a head onto the magnetic disk surface. The lubricating film comprises at least two kinds of lubricating agents each of which forms an individual layer, the layers being laminated. An adhesion enhancing layer is formed between a magnetic film and a lubricating agent at the surface of the magnetic disk, and the adhesion enhancing layer is fixed onto the magnetic film surface. Then, the adhesion enhancing layer and the lubricating agent are combined. The adhesion enhancing layer and the lubricating agent form a salt or complex body, and the lubricating agent can repeat adsorption and desorption with the adhesion enhancing layer reversely by a thermal reaction.

Magnetic disk, and magnetic disk apparatus

The magnetic recording medium includes at least a substrate, a magnetic film formed on the substrate for storing data, a protective film and a lubricant film. The protective film has two regions of a predetermined pattern each having a different surface energy. The lubricant film including polar groups is formed on the protective film including the regions. The degree of adhesion of the lubricant film to the protective film is thus changed at the two regions each having a different surface energy so that the lubricant film can be prevented from being scattered.

Magnetic recording medium having a protective layer which includes high

A highly reliable rotary magnetic recording medium has a lubricating film layer on its surface, the lubricating film layer being composed of fluoropolyether having at least two acidic functional groups in one molecule as a lubricant and fluoropolyether having at least two basic functional groups in one molecule as another lubricant, where a stable network structure is formed on the surface of the magnetic recording medium by an appropriate combination of the lubricant having the acidic groups at the terminal ends of lubricant molecule and the lubricant having the basic groups at the terminal ends of lubricant molecule.

Magnetic recording medium having a lubricant layer comprising ionically

A coating type, magnetic disk is produced by applying a magnetic paint containing magnetic powders in a dispersed state to a non-magnetic substrate, thereby forming a magnetic recording film thereon, and applying surface waves to the magnetic recording film in an undried state. By applying the surface waves to the magnetic recording film, dispersibility and orientation of the magnetic powders are improved and a longitudinally oriented, coating type magnetic disk with distinguished electromagnetic properties, such as a high S/N ratio, etc. can be obtained.

Process for producing a rigid magnetic disk by longitudinally generating

Disclosed herein are a magnetic recording medium comprising a surface treatment layer provided on the surface of a magnetic coating film by use of a novel surface treatment agent capable of bonding to both magnetic particles and a binder in the magnetic coating film, and a process for producing the magnetic recording medium. It is possible to realize, with good productivity, a magnetic recording medium having excellent wear resistance and high reliability.

Magnetic recording medium comprising a surface treatment layer provided

A magnetic recording medium comprising a substrate, a ferromagnetic thin film formed on the substrate, and a protective film formed directly on the ferromagnetic think film, and a process for producing such magnetic recording medium. The expression 'formed directly' refers to the technique for forming the protective film on the ferromagnetic thin film so that the interface therebetween is free from contamination by, for instance, conducting the protective film formation under the vacuum used when forming the ferromagnetic thin film.

Magnetic recording medium and process for producing the same

A method for magnetic orientation of a magnetic recording medium using Meissner effect of a superconductor and a system therefor and a magnetic recording medium produced thereby. The magnetic particles of plate hexagonal barium ferrite in the magnetic coating are allowed to orient in the longitudinal direction thereof so that a magnetic recording medium having a magnetic orientation in such direction with the magnetic particles can be obtained.

Method for magnetic orientation of magnetic recording medium using

A fluorine-containing isocyanate derivative, wherein the isocyano group of the fluorine-containing isocyanate is protected, a fluorine-containing polymer having at least one acylazido group, a process for producing an information recording medium by applying a lubricant comprising the fluorine-containing isocyanate derivative or the fluorine-containing polymer having at least one acylazido group to a magnetic layer formed on a substrate directly or through an underlayer, or to a protective layer formed on the magnetic layer, then reproducing or forming an isocyano group and subjecting the isocyano group to polymerization, thereby forming a fluorine-containing isocyanate polymer layer, an information recording medium produced according to the process and an apparatus for information recording, using the information recording medium are disclosed. The lubricant is resistant to water and no polymerization proceeds before the formation of a lubricant layer, and a lubricant layer without defects is obtained with the lubricant and an information recording medium with good sliding characteristics is obtained.

Process for producing information recording medium

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 magnetic recording medium is prepared by applying a magnetic paint containing at least magnetic particles and a thermally curable binder to a substrate, thermally curing the applied magnetic paint, thereby forming a magnetic film, and impregnating micropores formed in the magnetic film with a lubricant, where the magnetic paint further contains a poly(alkyleneoxide)-grafted binder, and the grafted poly(alkyleneoxide) moiety is thermally decomposed during the thermal curing, thereby forming the micropores in the magnetic film. A large number of micropores having a pore size of not more than 0.1 .mu.m are formed in the magnetic film, and a magnetic disk of high durability with less noises and errors during the recording and reproduction can be obtained.

Process for producing magnetic recording medium, magnetic paint, and

A magnetic recording medium which has a magnetic coating film that contains magnetic particles in a binder and which further has a lubricating layer formed on the magnetic coating film. The magnetic coating film has a surface that is processed with both a fluorinated surface treatment agent that bonds to the magnetic particles and a fluorinated surface treatment agent that bonds to the binder. The magnetic recording medium exhibits markedly improved sliding strength when the surface treatment agents and the lubricant have similar molecular structures. It is particularly preferred that the fundamental skeleton in the molecular structure of the surface treatment agents and the lubricant consists of a perfluoropolyether chain.

Magnetic recording medium

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Tokyo, Japan

Heigo Ishihara